KR102802966B1 - Wire and cable forming system and method - Google Patents

Abstract

Systems and methods for manufacturing wire and cable products from polymer cable components are provided. The systems and methods include increasing the stiffness of the polymer cable component to reduce compression and strain of the cable component during manufacturing. In some cases, the stiffness is temporarily increased prior to or during the process of creating a strand or during the cabling process.

Description

Wire and cable forming system and method

Cross-reference to related applications

This application claims the benefit of U.S. Provisional Application No. 63/041,878, filed June 20, 2020, which is incorporated herein by reference in its entirety.

Field of invention

The present disclosure relates to producing communication cables, and more particularly to controlling the hardness of polymer cable components to produce high performance communication cables having reduced crush ratios.

When transmitting power or signals, a variety of means may be utilized. The invention disclosed herein generally focuses on wire and cable products that utilize insulating coated conductors to transmit current.

When designing wire and cable products, many factors must be considered. Applications such as Ethernet, CATV, and factory floor-based systems may dictate specific design features such as size, electrical characteristics, and physical properties. For size, it may be important that the cable fit into standard connections, conduits, distribution pipes, and wireways. For electrical characteristics, capacitance, inductance, DC resistance, current-carrying capacity, and voltage-carrying capacity may be design considerations. For certain special high-bandwidth cables, additional electrical parameters such as attenuation, propagation velocity, delay skew, impedance, insertion loss, and noise mitigation may be important. For physical properties, flame and smoke resistance, chemical resistance, ozone resistance, moisture resistance, and/or traction strength are common properties to consider. Fortunately, there are many tools and equations available to assist design engineers in considering the best options for constructing wire and cable products.

The process for manufacturing wire and cable is typically continuous in nature. A continuous manufacturing line typically includes a pay-out where material is unwound or dispensed to begin the line process. There may be an accumulator to help secure a portion of the unwound material to facilitate a consistent line speed. At the end of the line is a take-up which may also have an accumulator to allow the manufactured product to be manufactured at a consistent line speed and for the finished product to be wound onto rolls or other forms of packaging. These types of operations may include, among others, insulation, twinning, cabling, braiding, jacketing, and laying out wire and cable products into set lengths. In most wire and cable products, the first step is the insulation process. This is where the conductors are coated or covered with a polymeric material to electrically insulate them.

During and after the insulation process, forces may be encountered that may affect the ability of the final product to meet its intended specifications. For example, in the case of coaxial cables, it is desirable to add foil and/or metal braid to protect the inner insulation layer and the electrical signals contained therein. It is well known that metal braiding equipment can create indentations along the surface of the insulation it surrounds. In other words, since the insulation surface is often more ductile than the metal wires applied over it, the bare strands of the braided shield wire will deform the surface of the insulation underneath. These deformations of the insulation can affect the ability of the final cable to transmit signals as the capacitance and insertion loss increase. To account for these depressions, the design engineer may add extra insulation material to account for the depth of the impression.

In multiconductor cables, the various insulated conductors are often brought together by a twisting mechanism, often called a twinner, buncher, or cabler. The forces encountered in each of these mechanisms can compress and deform the polymer components of the cable. Again, the cable designer may add insulation to compensate for any compression, thus increasing the size and cost of the final product. Similar compressive forces may be experienced during jacketing and laying operations. To compensate for any deformation caused by the compression forces, thicker and/or stiffer jacketing layers may be used, which adds both size and cost to the final product.

Sometimes the opposing or compressive forces acting on the cable components can be periodic in nature. For example, if the wheel is not properly aligned, it may wobble back and forth as it traverses the circular rotation. This can create a sinusoidal deformation of the material. If this sinusoidal pattern coincides with the intended application frequency (or a harmonic thereof), signal integrity can be compromised. Conventional methods to help reduce the effects of these forces, whether coherent or sinusoidal in nature, include reducing the speed of the manufacturing line. The speed can be reduced to relieve and reduce the compressive forces introduced by the manufacturing equipment as the product is manufactured. For this reason, it is common for the equipment to be operated at a fraction of its potential speed. However, this is not desirable because the equipment cannot be utilized to its full potential.

Another way in which compressive forces can potentially create problems is with capacitive targets. Capacitance is a function of the distance between metal surfaces and the properties of the material between the metal surfaces. In the case of wires and cables, conductive surfaces may include, among other things, two closely spaced conductors or a closely spaced shield and conductor. The distance between these conductive surfaces is a key design consideration when manufacturing wire and cable products. Therefore, care must be taken to ensure that adequate conductor-to-conductor distance is achieved.

In some embodiments, two insulated conductors are formed together to form a twisted pair. Similarly, many insulated conductors may be formed together to form a multi-conductor cabled unit. When two insulated conductors are twisted together, a helical pattern is achieved along the length of the twisted unit. The twisted unit typically consists of a metallic conductor, an insulating material, and air contained within the gap of two generally circular insulated conductors. It is well known that air is a very desirable dielectric material. For example, air has a permittivity of 1.0, while materials such as polyolefins have a typical permittivity range of 2.3 to 2.6. Therefore, the more air that is retained within the gap of the twisted unit, the more desirable the electrical results. However, since the compressive forces encountered during the cabling process force these insulated conductors closer together, the insulating material may be displaced into these gaps, thus reducing the total air content. The result can be higher, usually less desirable, capacitance and, in some cases, reduced signal speed which can reduce the ability of the signal to propagate.

Insulated conductors, such as twisted pair telecommunication cables, are typically used for high frequency signal transmission in the plenum area of a building. In a twisted pair data cable embodiment, the individual conductive wires are insulated using a polymer, and then two of these insulated conductors are twisted around each other to form a single strand. A twisted pair cable typically consists of a plurality of strands contained within a single outer jacket to form the cable. Each strand within the cable may be twisted in a different lay (typically measured in mm/turn) to reduce electrical coupling (i.e., crosstalk) between adjacent strands.

The process of twisting the individual insulated conductors together often compresses the polymer insulation layer. The amount of force that compresses the insulation layer varies depending on the twisting equipment and the tightness of the twist (i.e., the number of turns per inch). The compressive force caused by twisting the insulated conductors causes deformation of the insulation layer and a decrease in the thickness of the insulation layer separating the two conductors. This causes an increased capacitance measured between the two conducting wires, and thus a decrease in the overall impedance of the stranded unit.

It should also be noted that in the case of twisting forces (the type or force encountered when the insulated conductors are twisted together), the deformation may not be uniform. This is because the insulation may be displaced unevenly depending on the direction of the twisting force. This is particularly undesirable in balanced pair applications. For example, in some applications involving a twisted pair unit having two insulated conductors, it is desirable for the signal within each of the two insulated conductors to be a mirror image of the other conductor. In this way, electrical noise coupled into each insulated conductor of the twisted unit couples in the same manner, thereby allowing electronic filtering mechanisms to remove the noise component. When the geometry of one insulated conductor within the pair is unbalanced, it becomes difficult to subtract any noise component from the desired signal. Often, specifications for wire and cable products have both near-end and far-end crosstalk specifications to ensure that the amount of noise between the transmission pair is sufficiently low so as not to interfere with signal transmission. If the insulated conductors are not well balanced, the ability to meet these specifications may become more difficult.

When considering how much additional insulation material is needed to compensate for any insulation displacement or deformation resulting from forces encountered during the manufacturing process, the ductility of the insulation material must be understood. Since these are generally permanent displacements and deformations, it is most appropriate to understand the hardness of the compound. Hardness, often expressed in Pascals, measures the resistance of a material to surface deformation. In other words, hardness is the resistance to localized surface deformation. Indentation hardness can be measured by a variety of methods, including Brinell, Meyer, Vickers, Rockwell, and/or Shore hardness scales. For polymeric materials such as fluorinated ethylene propylene (FEP), polyethylene (PE), polypropylene (PP), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyvinyl chloride (PVC), etc., the Shore D hardness scale is commonly used. For other materials, such as rubber, other Shore scales, such as Shore A, may be used. For Shore D, the test protocol is defined in ASTM D2240 and/or ISO 868 and will be used here as the baseline hardness standard.

It is understood that changes in ambient temperature conditions can affect the ductility of a material. For example, in warm climates, temperature control of the manufacturing site may be required during the months when ambient temperatures are seasonally high, thereby reducing the stiffness of any polymeric material in the manufacturing site. Additionally, when a cable component is subjected to compressive, torsional, or other straining forces, heat is generated within the cable component. In some applications, the forces involved increase the temperature of the component above the ambient temperature as the component deforms, thereby reducing the stiffness of the component and increasing its susceptibility to deformation during that deformation event as well as any subsequent deformation events.

Conversely, if the compound is cooled below ambient temperature, the hardness of the compound may increase. This hardening may make the material more resistant to compressive forces that could deform the material or cause indentations in the material.

The temperature adjustment need not persist beyond the compression event. Since the deformations described herein are inherently permanent (i.e., not elastic), the disclosed methods need only be applied prior to or during the compression event. Once the compression event is over, the material may be allowed to return to ambient temperature. Other methods described above are inherently more permanent (such as mechanical slowdown, adding a skin layer, or adding a stiffer material to the insulation). By utilizing a temporary adjustment of the material hardness, many of the adverse effects of these solutions can be avoided.

It is desirable in the industry to have a method of hardening the compound or reducing the applied compressive force, which is less costly than adding insulation to counteract the effect of straining the polymer cable component. It is also desirable that any method incorporated to reduce the effect of compressive force on the insulation be able to fit within current machinery footprints with little or no modification to the positioning of the equipment itself. One such method is to control the temperature of the compound to produce a shift in the hardness of the compound. It is understood that a harder compound will be less affected by compressive force than a softer compound. When using the Shore D scale, a higher number indicates a harder state of the compound. This takes the same material type, the only change being the temperature of the material itself.

As previously mentioned, reducing the deformation caused by forces encountered during the manufacturing process can improve performance and reduce costs. Both can be achieved by shifting the material hardness through a temporary temperature change.

By increasing the stiffness of the polymer cable component, the deformation of the polymer insulation layer, cross web filler, polymer tube, or other polymer cable component can be reduced. This deformation is typically caused by compressive or torsional forces during manufacturing operations such as twisting, braiding, or mechanical devices such as pulleys (wheels) and windings.

A cost-effective method of increasing the harness of a material is required. A method of cooling an insulating material at or near the point where a compressive force is applied is required. In this manner, the hardness of the material can be increased compared to when it is at ambient temperature and the deformation caused by the compressive force can be reduced.

The present disclosure generally relates to the production of wire and cable products including methods for temporarily changing the hardness and/or Young's modulus of a material.

Some disclosed embodiments relate to methods and devices for increasing the hardness and/or Young's modulus of polymeric insulation, which may be used inline as part of a continuous or semi-continuous manufacturing process. Some disclosed embodiments relate to methods for reducing the effect of a compressive force on a polymeric cable component, the methods comprising: providing a polymeric cable component having a first hardness, which is a hardness of the polymeric cable component under ambient conditions; temporarily changing the hardness of the polymeric cable component to a second hardness, wherein the second hardness is different than the first hardness; applying a compressive force to the polymeric cable component; and allowing the polymeric cable component to return to the first hardness.

Some disclosed embodiments relate to a method of forming a strand, comprising: providing a first polymer insulated conductor comprising a first conductor electrically insulated by a first polymer insulating layer and a second polymer insulated conductor comprising a second conductor electrically insulated by a second polymer insulating layer; exposing the first insulated conductor to a cryogenic fluid; and twisting the first and second polymer insulated conductors around one another to form a strand.

In some embodiments, a polymer cable component, such as a polymer insulated conductor, is exposed to a cooled fluid for different periods of time to adjust the hardness of the polymer cable component. In some embodiments, a polymer cable component, such as a polymer insulated conductor, is exposed to a cooled fluid for different periods of time to produce a cable having reduced delay skew.

Some disclosed embodiments relate to methods of manufacturing communication cables to reduce deformation of polymer cable components and preserve the circularity of the insulating conductors and other cable components.

Some of the disclosed embodiments relate to equipment for systems for manufacturing wire and cable products having improved electrical properties. Some of these embodiments relate to cooling vessels and/or secondary structures for holding a cooling medium, such as, for example, a cooled fluid or a cooled solid surface.

Several of the disclosed embodiments relate to methods of manufacturing communication cables having reduced fuel loads. Several of these embodiments relate to methods of forming wire and cable products having lower total polymer insulation than conventional cables, such that the cables have lower total fuel loads and improved flammability and/or smoking characteristics. Several of the disclosed embodiments relate to methods of manufacturing communication cables at higher speeds. Several of these embodiments relate to operating the twinning apparatus at higher speeds, which typically increases the compressive force on the polymer insulation layer. Several of these embodiments relate to curing the polymer insulation prior to twinning so that the twinner can be operated at higher speeds and still produce cables having acceptable strain and desired electrical properties.

The disclosed invention may be applied to any form of polymer cable component or cable structure, including for example solid, foam, profile extrusion, insulation layer, hollow tube, cross web, load filler, film, tape, coaxial structure involving braiding process and/or multilayer insulation.

In addition to reducing deformation of the insulation layer as the insulating wire is twisted into a strand, the disclosed invention may also be used to reduce deformation of any polymeric material exposed to compressive forces, such as, for example, braided impressions or mechanical systems such as windings, pulleys or wheels.

The above provides a simplified summary to provide a basic understanding of some aspects of the claimed subject matter. This summary is not an extensive overview. It is not intended to identify key or critical elements or to delineate the scope of the claimed subject matter. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented below.

The accompanying drawings, which are incorporated in and form a part of this specification, illustrate several aspects of the present disclosure and, together with the description, serve to explain the principles of the present disclosure:
FIG. 1 illustrates a schematic cross-sectional view of an embodiment of an insulated conductor according to the present disclosure.
Figures 2a and 2b illustrate schematic cross-sectional views of an embodiment of a longitudinal line.
FIG. 3 illustrates a schematic cross-sectional view of an embodiment of an insulating conductor according to the present disclosure.
FIGS. 4A to 4C illustrate schematic diagrams of embodiments of cooling vessels according to the present disclosure.
FIGS. 5A and 5B illustrate schematic diagrams of embodiments of a cooling vessel having a secondary structure according to the present disclosure.
Figure 6 shows a graph of compression ratio data.
Figure 7 shows a graph of surface temperature data and compression ratio data versus exposure time.
Figure 8 shows a cross-sectional image of a foam insulating conductor.
Figure 9 shows a graph of surface temperature data for foam and solid polymer insulation versus exposure time.
Figure 10 shows the temperature of the foam and solid polymer insulated copper conductors over time.
Figure 11 shows the temperature of the foam and solid polymer insulated copper conductors over time.
Figure 12 illustrates a schematic diagram of an embodiment of a wire according to the present disclosure.
FIG. 13 illustrates a drawing of an embodiment of a cable according to the present disclosure.
FIG. 14 illustrates a schematic cross-sectional view of an embodiment of a cable according to the present disclosure.
FIG. 15 illustrates a schematic cross-sectional view of an embodiment of a cable according to the present disclosure.
FIG. 16 illustrates a schematic cross-sectional view of an embodiment of an insulating conductor according to the present disclosure.
FIG. 17 illustrates a schematic cross-sectional view of an embodiment of a cable according to the present disclosure.
FIG. 18 illustrates a schematic diagram of an embodiment of a cable according to the present disclosure.
FIGS. 19A to 19C illustrate schematic diagrams of embodiments of cooling vessels according to the present disclosure.
FIGS. 20A to 20C illustrate schematic diagrams of embodiments of cooling vessels according to the present disclosure.
Figure 21 shows a graph of the Shore D hardness of solid FEP versus exposure time to liquid nitrogen.
Figure 22 shows a graph of the Shore D hardness of solid FEP versus exposure time to ambient atmosphere after exposure to liquid nitrogen.
Figures 23a through 23c illustrate graphs of Shore D hardness of solid FEP versus exposure time to ambient atmosphere after exposure to liquid nitrogen.
Figure 24 shows a graph of the Shore D hardness of foam FEP versus exposure time to liquid nitrogen.
Figure 25 shows a graph of the Shore D hardness of foam FEP versus exposure time to ambient atmosphere after exposure to liquid nitrogen.
Figure 26 shows a graph of the Shore D hardness of foam FEP versus exposure time to ambient atmosphere after exposure to liquid nitrogen.
Figure 27 shows a comparison of the Shore D hardness of solid and foam FEP with respect to exposure time to liquid nitrogen.
Figure 28 shows a comparison of the Shore D hardness of solid and foam FEP versus exposure time to ambient atmosphere after exposure to liquid nitrogen.
Figure 29 shows a comparison of the temperature of solid and foam FEP versus exposure time to ambient atmosphere after exposure to liquid nitrogen.

The embodiments described below present information necessary to enable one of ordinary skill in the art to practice the present disclosure and illustrate the best mode of practicing the present disclosure. Upon reading the following description in light of the accompanying drawings, one of ordinary skill in the art will be able to understand the concepts of the present disclosure and recognize applications of these concepts that are not specifically addressed herein. It is to be understood that these concepts and applications fall within the scope of the present disclosure and the appended claims.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will also be understood that terms defined in commonly used dictionaries, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of this disclosure, and should not be interpreted in an idealized or overly formal sense unless explicitly defined as such in this disclosure. Known functions or configurations may not be described in detail for the sake of brevity or clarity.

The terms "about" and "approximately" will generally mean an acceptable degree of error or variation for a given measured quantity given the nature or precision of the measurement. A typical exemplary degree of error or variation is within 20 percent (%) of a given value or range of values, preferably within 10 percent, more preferably within 5 percent. The numerical quantities given in this detailed description are approximate unless otherwise stated, meaning that the terms "about" or "approximately" can be inferred when not explicitly stated. The numerical quantities in the claims are exact unless otherwise stated.

When a feature or element is referred to as being "on" another feature or element, it will be understood that it may be directly on the other feature or element, or that intervening features and/or elements may also be present. In contrast, when a feature or element is referred to as being "directly on" another feature or element, no intervening features or elements are present. When a feature or element is referred to as being "connected," "attached," or "coupled" to another feature or element, it will also be understood that the feature or element may be directly connected, attached, or coupled to the other feature or element, or that intervening features or elements may be present. In contrast, when a feature or element is referred to as being "directly connected," "directly attached," or "directly coupled" to another feature or element, no intervening features or elements are present. Features and elements that are described or illustrated with respect to one embodiment may be applied to other embodiments.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural as well, unless the context clearly dictates otherwise.

Although the terms "first," "second," etc. are used herein to describe various features or elements, these features or elements should not be limited by these terms. These terms are only used to distinguish one feature or element from another feature or element. Thus, without departing from the teachings of the present disclosure, a first feature or element described below could be termed a second feature or element, and similarly, a second feature or element described below could be termed a first feature or element.

Terms such as "at least one of A and B" should be understood to mean "A only, B only, or both A and B." The same interpretation should apply to longer lists (e.g., "at least one of A, B, and C").

The term "consisting essentially of" means that in addition to the elements described above, the claimed thing may also include other elements (such as steps, structures, components, elements, etc.) that do not adversely affect the operability of the claimed thing for its intended purposes stated in the disclosure. This term excludes such other elements that adversely affect the operability of the claimed thing for its intended purposes stated in the disclosure, even if such other elements might enhance the operability of the claimed thing for some other purposes.

In some places, reference is made to standard methods, such as, but not limited to, measurement methods. It should be understood that such standards are subject to revision from time to time, and unless otherwise expressly stated, references to such standards in this disclosure should be construed as referring to the most recently published standard as of the filing date.

The present disclosure describes embodiments of methods and systems for producing wire and cable products having improved electrical performance and/or improved manufacturing characteristics. While the disclosed invention is generally described in the context of twinning polymer-insulated wires to form stranded conductors, it will be appreciated that the disclosed invention is applicable to many applications other than twinning insulated conductors, including, for example, polymer insulation layers, foam insulation layers, foam jackets, cross webs, polymer tapes, hollow tubes, rod fillers, jacketing, and other polymer cable components.

When polymer cable components, such as insulated conductors, are subjected to compressive forces, such as when twinning wires to form a strand, the polymer components may compress or otherwise deform. In the case of polymer insulation layers, such deformation can disrupt the spacing between conductors in the conductive wires and affect the electrical performance of the wires or the final cable.

FIG. 1 schematically illustrates a cross-section of an insulated wire having a polymer insulation layer (110) around a conductor (120). When the insulated wire is subjected to a force, the insulation layer (110) may be deformed. The degree to which the insulation layer (110) is deformed may be described by the compression ratio. The compression ratio is defined as deformed length/original OD ^* 100 and is expressed as a percentage.

FIG. 2a schematically illustrates a cross-section of two insulated wires each having a polymer insulation layer (210) around a conductor (220). FIG. 2a illustrates that the two insulated wires are in contact with each other and that the circular polymer insulation layer is not deformed. The shaded area of the polymer insulation layer (210) in FIG. 2a illustrates the area that is deformed by the compressive force when the two wires are twinned together.

Fig. 2b schematically illustrates a cross-section of two insulated wires each having a polymer insulation layer (210) around a conductor (220). Fig. 2b illustrates the two wires in contact with each other after a compressive force has caused deformation in the polymer insulation layer.

Comparing the inter-conductor distance of the uncrimped wire of Fig. 2a to the crimped wire of Fig. 2b shows that the distance between the two conductors is reduced due to deformation of the two insulating layers. This type of compression can occur when the wires are twinned together or during other compression events. This reduction in the inter-conductor distance negatively affects the electrical performance of the twinned wire and any resulting cable.

The forces applied to polymer cable components depend on the type and manufacturer of equipment utilized by any particular wire and cable company. For example, there are many different types of cabling machines. Each of these machines will present unique forces to the various elements being cabled. When a wire and cable manufacturer determines how much additional insulation should be incorporated into the design to compensate for strain, it is often experience combined with knowledge of the material harness that will ultimately determine how much additional insulation will be required.

Within the industry, the term "wall thickness" is used to determine how much insulation and/or jacketing material is required to produce a desired product. Most application designs will have an absolute minimum wall thickness, an average minimum wall thickness, a nominal wall thickness, and an absolute maximum wall thickness. When compensating for insulation layer deflection and settlement, the nominal wall thickness is typically considered.

The more ductile the insulation material, typically the more additional wall thickness is required to compensate for the wall thickness lost to compression under a given set of conditions. For example, FEP is a more ductile insulation than HDPE or PP and will require a greater amount of additional insulation. Understanding the stiffness of the insulation material is useful in determining the amount of compensation needed. If the strain is better controlled, the amount of additional insulation needed can be reduced. This will aid in both the size and cost of the final product. In some embodiments, the amount of additional insulation added to produce a desired cable is reduced by at least about 0.0005 inches, or by at least about 0.001 inches, or by at least about 0.003 inches, or by at least about 0.005 inches, or by at least about 0.01 inches, compared to a cable produced under the same conditions without using the cooling techniques described herein.

Softer insulating polymers, such as fluorinated ethylene propylene (FEP), are more likely to exhibit increased deformation when forces are applied to the insulation compared to insulation layers made from harder polymers. Foam insulation layers may also be more sensitive to deformation than solid polymers.

The resistance to deformation of an insulating layer can generally be measured or described by the hardness of the insulating material. As described, hardness is a measure of the resistance to localized plastic deformation induced by mechanical indentation or wear. Typically, different materials have different hardnesses. In some embodiments, Young's modulus may also affect the amount of deformation that occurs as a result of a compressive force. Young's modulus is a mechanical property that measures the stiffness of a solid material in the elastic region, rather than the plastic region. It defines the relationship between stress (force per unit area) and strain (deformation) in a material. The higher the Young's modulus, the less elastically the material will deform under the same force.

One way to increase the hardness and Young's modulus of the polymer insulation layer is to cool the polymer material. Such cooling may be accomplished by any suitable method, such as, for example, directly or indirectly exposing the material to a cooled fluid, such as a cooled liquid or gas. In some embodiments, the polymer cable component may be exposed to cooled water or an aqueous solution. In some embodiments, the polymer cable component may be exposed to a cryogenic fluid, such as liquid nitrogen. In some embodiments, the polymer cable component may be exposed to a cooled gas or vapor. In some embodiments, the polymer cable component may be exposed to one or more cooled wheels, rollers, tubes, or other solid surfaces. In some embodiments, the polymer cable component may be cooled indirectly. For example, the polymer cable component may be passed through the interior of the tube while the exterior of the tube is cooled. The atmosphere within the tube will cool, thereby cooling the polymer cable component. While the invention described herein is generally described in the context of cryogenic fluids, it will be appreciated that any of these methods may also or alternatively be used.

In some circumstances, the time required to cool the entire thickness of the polymer insulation layer may be impractical. In one embodiment, the disclosed invention cools the outer surface of the insulation layer without cooling the inner bulk of the insulation layer to the same extent. In some embodiments, cooling only the outer portion of the insulation layer helps reduce the overall strain in the insulation layer, since the outer surface is typically the portion of the insulation layer that is subject to the most compressive forces during manufacturing.

FIG. 3 schematically illustrates a cross-section of an insulated wire having a polymer insulation layer around a conductor (340). The insulation layer of the embodiment illustrated in FIG. 3 is a single homogeneous polymer layer, but FIG. 3 illustrates the homogeneous insulation layer as being divided into separate concentric portions for clarity. The outer surface (310) of the polymer insulation layer is generally exposed to the external environment and is subjected first to any external compressive force. The outer portion (320) of the insulation layer is directly beneath the outer surface. The inner bulk of the insulation layer (330) is subjected to the least external compressive force because it surrounds the conductor (340) and both the outer surface (310) and the outer portion (320) of the insulation layer must deform before the inner bulk (330) is affected.

When the polymer insulated wire is exposed to a cold liquid or a cryogenic fluid, such as liquid nitrogen, the outer surface (310) will rapidly cool as it comes into direct contact with the cryogenic fluid. The outer portion (320) of the insulation will cool next as heat is drawn out of the insulation and into the cryogenic fluid. The rate at which the outer portion of the insulation cools will vary based on the thermal conductivity of the polymer material forming the insulation. The inner bulk (330) of the insulation will cool after the outer surface and outer portion. It will be appreciated that a temperature gradient will form rather than a sharp line separating the outer portion (320) from the inner bulk (330).

As the outer surface and outer portions of the insulation layer cool, the hardness of these portions of the insulation layer will increase. In some embodiments, this creates a hardened "skin" on the outer portion of the insulation layer surrounding the relatively higher temperature inner bulk of the insulation layer.

If the insulation is kept in contact with the cryogenic fluid for a sufficiently long period of time, eventually the entire bulk of the insulation will cool, resulting in an increase in the hardness of the entire insulation. However, wire and cable manufacturing facilities typically produce cables at relatively high rates. To cool the entire thickness of the insulation while the cable is moving at relatively high rates, the length of the cooling equipment may need to be longer than is desirable for a particular application. By using embodiments of the disclosed invention, the length of the required cooling equipment may be reduced, and deformation of the insulation may be minimized. By creating a cured outer skin within the homogeneous polymer insulation layer, the squeezing ratio may be reduced when the insulation wires are twinned together or when the polymer insulation wires are exposed to other external compressive forces.

When the polymer insulating conductor is removed from the cryogenic fluid or other cooling medium and exposed to the ambient atmosphere, it will be appreciated that the polymer insulating material will begin to return to the ambient temperature. As the temperature increases, the hardness of the polymer insulating material will decrease, and the polymer insulating material will become more susceptible to deformation by compressive forces. In some embodiments of the disclosed invention, the polymer insulating layer or layers are cooled just prior to being subjected to a compressive event, such as, for example, twinning to form a strand. In some applications, the speed at which the insulating conductor is moved and the distance between the cooling vessel and the twinner winding will determine the length of time that the polymer insulating conductor is exposed to the ambient atmosphere after cooling but before being subjected to compressive forces. In some embodiments, the end of the cooling vessel is less than 10 feet from the point at which the polymer insulating conductor is subjected to subsequent compressive forces. In some embodiments, the end of the cooling vessel is less than 8 feet, 6 feet, 4 feet, or 2 feet from the point at which the polymer insulating conductor is subjected to subsequent compressive forces.

It will be appreciated that the harness of a given material is dependent on the temperature of that material. Accordingly, as the temperature of a given material increases and decreases, the hardness decreases and increases, respectively. In some embodiments, the material will be cooled, thereby increasing the hardness just prior to the compressive force and then allowing it to return to ambient temperature. Increasing the hardness during the compressive force, even if the hardness is only temporarily increased, can help the material resist deformation due to the compressive force.

It will be appreciated that the disclosed invention does not require any change in the composition of the polymer insulating material. The composition of the polymer insulating layer remains constant while the polymer insulating material cools, thereby increasing its hardness. The composition of the polymer insulating layer remains constant as the insulating material is subjected to any compressive or deforming force and as the polymer insulating material is allowed to return to ambient temperature, thereby decreasing its hardness.

In some embodiments, the conductor may be insulated by more than one layer of insulating material. In some embodiments, the conductor may be insulated by, for example, a polymer foam layer and also a solid polymer layer. In some embodiments, the multiple layers of polymer insulating material may be made of different polymers. In some embodiments, the multiple layers of polymer insulating material may be made of the same polymer. Each layer of insulating material may be of a different thickness than any other insulating layer or may be of approximately the same thickness.

It will be appreciated that a thicker polymer insulation layer may require more time to reach a higher hardness than a thinner polymer insulation layer, since the temperature gradient needs to propagate into the bulk of the thicker polymer insulation layer. In some embodiments, the exposure time for which the insulating conductor is exposed to the cryogenic fluid may be adjusted based on the thickness of the polymer insulation layer.

In some embodiments, several of the conductors of each of the multiple strands contained within a single cable may be exposed to the cryogenic fluid for different periods of time. By controlling the length of time that the conductors are exposed to the cryogenic fluid, the degree of crimping and the final electrical properties of the strands can be controlled.

In some embodiments, by increasing the hardness of the polymer insulating conductor, the conductor will generally maintain its circular cross-section rather than deforming under compressive forces. This can reduce the amount of surface-to-surface contact between the two polymer insulating conductors and reduce frictional or torsional forces between the insulating conductors.

In some embodiments, the polymer insulated conductor or other polymer cable component is cooled to increase its hardness prior to being subjected to the compressive force. In some embodiments, the reduced temperature of the polymer cable component offsets any heat generated within the polymer cable component by the compressive force. In some embodiments, the temperature of the polymer cable component during or immediately following the compressive event is below the ambient temperature.

In some embodiments, the disclosed invention can be utilized to twine polymer insulated wires to form a strand. A stranded wire is typically manufactured by twisting two polymer insulated wires around each other using a machine referred to as a tweener. The process of twinning the wires to form a strand creates a compressive force between the two wires at the point where they contact each other. This compressive force increases as the pitch or twist rate of the strand increases.

The purpose of twinning wires to form a pair is to improve the electromagnetic compatibility of the wires. Twisted pair wiring reduces electromagnetic radiation from the pair and reduces crosstalk and electromagnetic interference between adjacent pairs compared to untwisted wires. A single pair of wires may be used to form a single-pair Ethernet cable, or multiple pairs of wires may be combined to form various other types of cabling, including Ethernet cabling. Preferably, each insulated conductor in the pair is a mirror image of the other insulated conductor in the pair. When two insulated conductors in a pair are mirrors of each other, this results in improved noise rejection between the insulated conductors and creates a balanced pair system. Often, the insulation layers around the conductors contained in a pair are affected differently by the compressive forces. This can cause differences between the two insulated conductors and can lead to imbalances, which can result in reduced noise rejection, which is undesirable in the end product.

In one embodiment, prior to feeding the polymer insulated wire into the twinning machine, the insulated wire is passed through a cooling vessel. In some embodiments, the cooling vessel exposes the insulated wire to a cryogenic fluid, thereby increasing the hardness of at least the outer surface of the polymer insulation layer. In some embodiments, the cooling vessel contains a pool of a cryogenic fluid, such as, for example, liquid nitrogen. In some embodiments, the cooling vessel contains a spray of the cryogenic fluid. It will be appreciated that the cooling vessel may be used to expose any polymer cable component to any form of cooling medium. For clarity, the disclosed invention will be described in the context of a cryogenic fluid, but it will be appreciated that chilled air or any other gas or vapor, as well as chilled water or any other chilled liquid or chilled solid surface, may be used.

FIG. 4A illustrates a schematic diagram of a cooling vessel (410) according to one embodiment. As shown in FIG. 4A, an insulated wire (420) may enter the cooling vessel (410) through an aperture (440) within the cooling vessel below the surface of the cryogenic fluid (430), thereby immersing the insulated wire into a pool of cryogenic fluid (430). The cooled insulated wire (420) may exit the cooling vessel (410) through a similar aperture (440) in the side of the cooling vessel. In some embodiments, a flexible gasket, membrane, or valve may be used to restrict the flow of cryogenic fluid out of the cooling vessel.

FIG. 4b illustrates another schematic diagram of a cooling vessel (411) according to one embodiment. In some embodiments, an insulated wire (421) is routed downward into a pool of cryogenic fluid (431) using a wheel, roller, or wire guide (441). This allows the cooling vessel to maintain a pool of liquid without leakage. In some embodiments, the cooling vessel includes a top or cover (not shown) having an opening that allows the wire to enter the cooling vessel and reduces overall loss of cryogenic fluid due to evaporation or dissipation.

FIG. 4C illustrates another schematic diagram of a cooling vessel (412) according to one embodiment. In some embodiments, the cooling vessel (412) is equipped with one or more nozzles (432) that spray a cryogenic fluid or other cooled liquid or gas onto an insulating wire (422). In some embodiments, the insulating wire (422) does not physically contact the cooling vessel or associated equipment, thereby avoiding any compressive forces prior to cooling. In some embodiments, the insulating wire enters and exits the cooling chamber through small holes (442) to be sprayed with the cryogenic fluid. Since there is no standing pool of cryogenic fluid in some nozzle embodiments, loss of cryogenic fluid is not a significant issue.

It will be appreciated that some embodiments include a combination of the cooling vessels described above. In some embodiments, multiple cooling vessels may be used in series to achieve a particular desired effect. In some embodiments, a single cooling chamber may have one, two, or multiple insulated conductors passing through the cooling chamber simultaneously. In some embodiments, a single cooling chamber may be used to cool two wires that are to be formed into a single strand. In some embodiments, a single cooling chamber may be used to cool a plurality of insulated wires that may be used to form a plurality of strands.

In some embodiments, the cold vessel may be at least about 2 feet long, or about 4 feet long, or about 6 feet long, or about 10 feet long, or about 15 feet long. In some embodiments, the cold vessel is at most about 20 feet long, or about 15 feet long, or about 10 feet long, or about 8 feet long, or about 6 feet long. In some embodiments, one or more pulleys, wheels, capstans, and/or rollers may be used within the cold vessel to redirect the path of the polymer cable component within the cold vessel. This arrangement may allow the polymer cable component to remain within the cold vessel for a longer period of time without increasing the length of the cold vessel or reducing the line speed of the component. In some embodiments, the polymer cable component enters the cold vessel in the upper vapor region of the vessel where the evaporated cryogenic vapor rises above the cryogenic liquid, and is then redirected through the liquid region of the vessel where the liquid cryogenic fluid remains. This arrangement allows the polymer cable components to initially transfer heat to the cryogenic vapor prior to contact with the cryogenic liquid, thereby reducing the total heat load transferred to the cryogenic liquid and increasing the total residence time of the polymer cable components within the cooling vessel.

The length of time that the insulated wire is exposed to the cryogenic fluid will depend on the length of the cooling vessel and the speed at which the insulated wire is moving. In some embodiments, the wire is exposed to the cryogenic fluid for at least about 1 second, or at least about 2 seconds, or at least about 4 seconds, or at least about 6 seconds, or at least about 8 seconds, or at least about 10 seconds. In some embodiments, the wire is exposed to the cryogenic fluid for at most about 30 seconds, or at most about 20 seconds, or at most about 10 seconds, or at most about 8 seconds, or at most about 6 seconds, or at most about 4 seconds.

In some embodiments, after exiting the cooling vessel, the insulated wire enters the tweener where it is twisted around the second cooled insulated wire to form a strand with less strain between the two insulation layers. In some embodiments, the insulated wire enters the tweener within about 1 second after exiting the cooling vessel, or within about 2 seconds after exiting the cooling vessel, or within about 4 seconds after exiting the cooling vessel. In some embodiments, the cooling vessel is positioned relative to the tweener or other device that applies a compressive force on the insulated wire such that the polymer insulated wire experiences a compressive force before the increased hardness of the polymer insulated wire is reduced by greater than about 10%, or greater than about 20%, or greater than about 30%. In other words, in some embodiments, the cooling vessel is positioned such that the polymer insulated wire exiting the cooling vessel experiences any subsequent compressive force before the polymer insulated wire significantly warms up and thereby reduces its hardness.

In some embodiments, one or more secondary structures may be positioned to maintain a cooler atmosphere around the polymer insulated conductor than the ambient temperature after it exits the cooling chamber. FIG. 5A illustrates an example of a cooling vessel (510) having a secondary structure (550) positioned around a polymer insulated conductor (520) as it exits the cooling vessel. In some embodiments, the secondary structure (550) is a hollow tube arranged to maintain a cooled atmosphere around the polymer insulated wire before the wire is subjected to compressive forces as part of the twinning process. The secondary structure (550) may be made of any thermally conductive material, including, for example, metals and/or polymers. In some embodiments, the secondary structure (550) may be a larger tube arranged to surround the plurality of wires as they exit the cooling chamber to maintain an increased stiffness before the wire is subjected to any compressive or deforming forces. In some embodiments, the secondary structure (550) may be a tube having an adjustable length that can be expanded and/or contracted to adjust the residence time of the polymer cable components within the tube. In some embodiments, the secondary structure includes a removable or openable portion, such as a top or cover. In such embodiments, the secondary structure may be opened to allow initial treading or lacing of the wire or cable line, and then closed to exclude the ambient atmosphere within the secondary structure and maintain a cooler atmosphere than the surroundings.

In some embodiments, the secondary structure is arranged to receive cryogenic fluid from the cooling vessel. In one example, the secondary structure may be arranged to receive cold nitrogen vapor from an evaporation pool of liquid nitrogen contained within the cooling vessel. By maintaining a cooler than ambient temperature atmosphere around the wire leaving the cooling vessel, the secondary structure may help maintain increased hardness as the wire moves from the cooling vessel to the compressive twinner or other subsequent stage. In some embodiments, any cryogenic fluid that leaks outside the cooling vessel is received by the secondary structure. In the case of a cryogenic liquid, the cryogenic liquid received in the secondary structure may evaporate within the secondary structure, thereby creating a cooled atmosphere within the secondary structure and preventing leakage of any cryogenic liquid onto the manufacturing site.

In some embodiments, the secondary vessel may be connected to the cooling vessel, the twinner, or both. In some embodiments, the secondary structure may direct cryogenic vapor from the cooling vessel through the secondary structure into the twinner for expansion or vaporization. In such embodiments, the atmosphere within the twinner may be maintained at a lower temperature than the ambient atmosphere surrounding the twinner.

Although the present invention is generally described in the context of exposing a polymer cable component to a cryogenic fluid, it will be appreciated that other methods of cooling a polymer cable component and thereby increasing its hardness may also be used.

In some embodiments, the polymer cable component may pass through the interior of a cooled tube. The exterior of the tube may be exposed to a cooling medium, such as a cooled or cryogenic fluid, thereby reducing the temperature of the tube itself. In such embodiments, the atmosphere within the cooled tube will be indirectly cooled by the cooled or cryogenic fluid as heat is drawn from the tube into the cooled or cryogenic fluid. The polymer cable component may be cooled by its exposure to the cooled atmosphere within the tube, thereby increasing the hardness of the polymer cable component. In some embodiments, the tube may be only slightly larger than the polymer cable component passing through the tube. The degree of cooling of the polymer cable component may be controlled by reducing the distance between the interior surface of the tube and the polymer cable component. In some embodiments, the tube may have a removable cover or hinged cover that allows the tube to be opened to facilitate initial lacing of the polymer cable component through the tube. Once the tube is closed, the exterior of the tube may be exposed to the cooled or cryogenic fluid to establish a cooled internal atmosphere within the tube. In some embodiments, the tube may be flexible or may utilize modular components to increase or decrease the length of the tube during continuous operation. In some embodiments, this allows the operator to adjust the total residence time of the polymer cable components within the cooled atmosphere of the tube without stopping production to change the tube, tube length, and/or tube components.

FIG. 5b schematically illustrates a cooled tube embodiment as described above. In the illustrated embodiment, the tube (610) passes through a cooled material (620), thereby creating a cooled atmosphere within the tube (610). The polymer cable component (605) passes through the cooled tube (610) and is exposed to the cooled atmosphere within the tube (610). In the illustrated embodiment, a heat exchanger (630) may be used to control the temperature of the cooled material (620). In some embodiments, the temperature of the cooled material (620) may be adjusted in response to the temperature of the atmosphere within the tube (610). In some embodiments, the cooled material (620) may be a cooled liquid circulating around the tube (610). As the atmosphere within the tube (610) increases beyond a desired range, the cooled liquid may be circulated more quickly, or the temperature of the cooled liquid may be decreased until the temperature of the atmosphere within the tube (610) drops to a desired range.

In some embodiments, the cooled tube includes an inlet hole or slit configured to allow a quantity of cooled material to move into the interior of the tube. The size, shape and number of these holes or slits may be arranged differently depending on the anticipated conditions. In some embodiments, the cooled material is a cryogenic liquid that is allowed to enter the tube through the hole or slit. This will reduce the temperature within the tube and also allow some direct contact between the polymer cable component and the cryogenic liquid. In some embodiments, the amount of cryogenic liquid allowed to enter the tube can be adjusted such that, under operating conditions, all of the cryogenic liquid that enters the tube evaporates within the tube. This will prevent the cryogenic liquid from leaking outside of the cooling device and will allow for faster and/or more complete cooling of the polymer cable component.

In some embodiments, cooled wheels, rollers, or pulleys may be used to increase the hardness of a polymer cable component. Wire and cable manufacturing is typically a continuous process involving a number of wheels, rollers, and/or pulleys for a variety of different purposes, such as directing the process, controlling tension, and/or stacking the cabling components. When a polymer cable component contacts these wheels, at least some compressive force is applied to the cable component. In some embodiments, a cooled or cryogenic fluid may be passed through the interior of the wheel, thereby cooling the wheel. As the solid surface of the wheel rotates, it may cool the polymer cable component in contact with the rotating surface without generating significant additional strain. When the polymer cable component contacts the wheel, it will cool at least slightly and will therefore become stiffer. In some embodiments, a series of cooled wheels, rollers, or pulleys may be used to increase the exposure time between the cable component and the cooled surface, thereby allowing the cable component to reach a desired degree of hardness before experiencing subsequent compressive forces.

In some embodiments, rather than using a liquid or solid cooling medium, cooled air or other cooled gas or vapor may be used to lower the temperature and increase the stiffness of the polymer cable components. Seasonal variation in wire and cable manufacturing is a known phenomenon. During the warmer months, a manufacturing facility may have a higher ambient temperature. This can lead to an increase in the temperature and a corresponding decrease in the stiffness of the polymer cable components used in that particular facility. To address this seasonal variation, some manufacturing facilities utilize standard air conditioning to maintain a relatively constant temperature within the facility. However, increasing the electrical performance of manufactured cables does not require maintaining a suitable temperature throughout the entire manufacturing facility.

In some embodiments, the air conditioning equipment may be used to direct cool air into the twinner or into a cooling chamber surrounding the polymer cable component. By reducing the temperature of the atmosphere surrounding the polymer cable component, the hardness of the polymer may be increased immediately prior to or during the compression event. In some embodiments, the air conditioning equipment may be used to generate air at a lower temperature than would be desirable throughout the manufacturing facility. In some embodiments, the air conditioning system may be configured to direct air at a temperature of less than about 60° F. over the polymer cable component. In some embodiments, the air conditioning or refrigeration system may be configured to direct air at a temperature of less than about 50° F., or less than about 40° F., or less than about 30° F., or less than about 20° F., or less than about 10° F., or less than about 0° F. over the polymer cable component. In some embodiments, the air conditioning or refrigeration system may be configured to induce air over the polymer cable component that is less than about 10° C., less than about 5° C., less than about 0° C., less than about -5° C., less than about -10° C., or less than about -15° C.

In some embodiments, the structure may be used to contain a colder atmosphere around the polymer cable component prior to or during the compression event. In some embodiments, a chamber around the twiner winding device may be used to contain a colder atmosphere than the surroundings. It will be appreciated that for some applications, special refrigeration equipment may be required to generate large quantities of very cold air. It will also be appreciated that cold air may be applied to the polymer cable component at any stage of the manufacturing process where increasing the hardness will help reduce deformation due to compression forces.

In one illustrative example, multiple strands of fluorinated ethylene propylene (FEP) insulated wire were produced at a line speed of 19 m/minute or about 63 feet/minute. The tweener parameters were set to 3,000 twists per minute and a twist length of 6.2 mm. Prior to entering the tweener, the wires were passed through a cooling vessel and immersed in liquid nitrogen for various periods of time. The crimp ratio of the final strands was examined using computed tomography (CT) scans.

Table 1 below presents the data collected over three trials. Each trial included four samples passed through cooling vessels of varying lengths. The cooling vessel lengths varied from 0 ft (control) to 2 ft, 4 ft, and 6 ft. Twinning parameters, including the aforementioned line speed, were held constant throughout all trials.

Table 1 - Crushing ratio

As can be seen from Table 1, the average compression ratio decreased with increasing length of the cooling vessel. A line speed of 19 meters/minute is approximately 1 foot per second, so the length of the cooling vessel in feet is approximately equal to the time, measured in seconds, that the insulated wire is exposed to liquid nitrogen.

Figure 6 illustrates a graph of the data presented in Table 1. As can be seen from the graph of Figure 6 and Table 1, the average crush ratio decreases from 6.74% when the FEP insulated wire was not exposed to liquid nitrogen, to 1.09% when the FEP insulated wire was exposed to liquid nitrogen for about 6 seconds. This represents a crush ratio reduction of about 83% in about 6 seconds.

Table 2 (below) shows the surface temperatures of samples of FEP insulated wire exposed to liquid nitrogen for various lengths. The surface temperatures were measured using a temperature probe as the FEP insulated wire passed through the cooling chamber and was twinned. The twinning parameters, including line speed, are consistent with the parameters described above.

[Table 2] - Surface temperature of FEP insulated wire

Figure 7 illustrates the data presented in both Tables 1 and 2 presented on a single graph. As can be seen from Figure 7, the surface temperature of the FEP coated wire dropped significantly after about 2 seconds of exposure to liquid nitrogen and then continued to drop at a slower rate. The compression ratio of the FEP insulated wire dropped after about 2 seconds of exposure to liquid nitrogen and continued to drop as the length of the cooling vessel and the time the wire was exposed to the liquid nitrogen increased.

The reduction in surface temperature of the insulation wire, as well as the corresponding reduction in the crimp ratio, indicates that it is not always necessary to expose the insulation wire to the cryogenic fluid for extended periods of time to reduce the crimp ratio. In some embodiments, it is not necessary to reduce the temperature of the entire thickness of the insulation layer to dramatically reduce the crimp ratio. The outer layer of the insulation layer can be cooled, thereby increasing the hardness of the outer portion of the insulation layer and reducing the crimp amount produced by twinning the insulation wire.

Without being bound by theory, the decreasing compression ratio is considered to be due to the increasing hardness of the outer portion of the FEP insulation wire. As the insulation wire is exposed to liquid nitrogen for a longer period of time, the thickness of the outer portion of the insulation layer with increased hardness increases. As the wire is exposed to liquid nitrogen for a longer period of time, the degree of hardness increase at the outer surface of the polymer insulation layer may also increase.

By exposing the polymer-insulated wire to liquid nitrogen or another cryogenic fluid for a short period of time, a skin of cured polymer may be formed within the homogeneous polymer layer. This cured polymer layer reduces deformation of the polymer insulation layer when the wire is exposed to an external force. By reducing deformation of the polymer insulation, the distance between conductors can be maintained more consistently. In some embodiments, by using the disclosed methods, the total amount of polymer insulation used can be reduced while maintaining the same distance between conductors. In some cases, reducing deformation of the polymer insulation layer increases the electrical performance of the wire and the resulting cable. Reducing the amount of deformation also assists in maintaining the shape of each insulated conductor, which improves electrical consistency between the two insulated conductors of the stranded wire and maintains the balance of the stranded wire.

In some embodiments, the outer surface of the polymer insulation layer is cooled to below 0° C. while the inner portion of the polymer insulation layer is maintained above about 5° C. In some embodiments, less than half of the thickness of the polymer insulation layer will have a temperature below about 5° C.

In some embodiments, the polymer insulation layer or a portion of the polymer insulation layer may be a foamed polymer. In such embodiments, the foamed polymer insulation includes many small air pockets created during the manufacturing process. Air is known to be a good electrical insulator, and therefore including air pockets throughout the polymer insulation layer reduces the dielectric constant of the insulation. This is because the dielectric constant of air is 1.0, which is preferable to the dielectric constants of other materials such as FEP (2.0), polyethylene (2.3), and polyvinyl chloride (3.5).

Air has excellent dielectric properties, but does not provide mechanical hardness. Therefore, a foam material or other polymer component that includes air will have a lower hardness than a similar component that does not include air. Since air can be incorporated into the polymer cable component in any number of ways (small cells, large cells, cavities, etc.), ultimately the strength will be reduced depending on the percentage of air replacing the solid polymer and the size of the air cavities utilized. In some embodiments, the methods for increasing hardness described herein are useful for increasing the hardness of the remaining polymer material that is not replaced by air. Since the foamed polymer is more sensitive to deformation than the solid polymer, the amount of additional material added to counteract the deformation may be increased. In some embodiments, the Shore D hardness of the foamed polymer material is increased by at least about 10% at 20° C., prior to or during the compression event, relative to a similar material.

Figure 8 illustrates a cross-sectional image of a foam insulation conductor having multiple air pockets distributed throughout the insulation layer. It will be appreciated that these air pockets are closed and do not allow air or any other fluid to move through the insulation layer.

In some examples, single wires insulated with foam FEP (rather than solid FEP) were twinned on a Setic Tweener and analyzed for compression ratio and electrical impedance. Samples of the foam FEP insulated wire were exposed to cryogenic fluid for various lengths of time. Samples exposed to the cryogenic fluid were compared to samples of the same foam insulated wire that were not exposed to the cryogenic fluid.

In one example, one pair of twinned wires was used as a control and was not exposed to any cryogenic fluid, whereas a similar pair of foam polymer-insulated wires was exposed to a liquid nitrogen bath for 5.6 seconds prior to twinning. The twist length of the twinned pair manufactured using both sets of wires was 8.5 mm. For this analysis, 6-inch samples of each of the two twinned pairs were imaged at three separate locations along their length using X-ray/CT.

As shown in Table 3 below, the average crimp ratio of the foam insulated twinned wires decreased from an average of 17.75% when the wires were not exposed to liquid nitrogen to an average of 12.92% when the twinned wires were exposed to liquid nitrogen for 5.6 seconds. This represents an improvement of 27.21%. The crimp ratio analysis was performed using X-ray/CT. Table 3 presents the crimp ratio data for each of the three points for the analysis for both the control and treated wires. The electrical impedance of the cryogenically cooled wires also increased from 136 ohms to 146 ohms, which is an increase of 10 ohms or 7.4% over the control wires.

[Table 3] - Compression ratio of foam-insulated twinned wire at 5.6 seconds

In another example, a second pair of FEP foam insulated twinned wires served as a control and were not exposed to any cryogenic fluid, while a similar pair of wires was exposed to a liquid nitrogen bath for 9.1 seconds prior to twinning. The twist length of the twinned pairs manufactured using these wires was 8.5 mm. Similarly, for this analysis, each 6-inch sample of the twinned pair was imaged at three separate locations along its length using X-ray/CT.

As shown in Table 4 below, the average crimp ratio of the twinned wires decreased from an average of 18.84% when the wires were not exposed to liquid nitrogen, to an average of 9.74% when the wires were exposed to liquid nitrogen for 9.1 seconds. This represents an improvement of 48.3%. The crimp ratio analysis was performed using X-ray/CT. Table 4 presents the crimp ratio data for each of the three points for the analysis for both the control and treated wires. The electrical impedance of the cryogenically cooled strands also increased from 142 ohms to 154 ohms, which is an increase of 12 ohms or 8.5% over the control strands.

[Table 4] - Compression ratio of foam-insulated twinned wire at 9.1 seconds

One of the advantages of the disclosed invention is the ability to produce stranded and/or other cable designs having improved electrical properties by increasing the stiffness and reducing the amount of strain generated during the twinning, cabling, and/or manufacturing processes. One source of strain in the insulation in a stranded cable is the twinning process, in which two insulated conductors are twisted around each other. The degree of strain that occurs during the twinning process is influenced by several factors, including, for example, the length of the twist, the wire tension, the insulation material, the stiffness of the insulation, and/or the amount of heat generated within the polymer insulation during the twinning process. In order to reduce the strain as much as possible, it may be desirable to increase the stiffness of the insulation material during the twinning process when the insulated conductors are subjected to the greatest strain. As described, one way to temporarily increase the stiffness of the insulation is to reduce the temperature. In some embodiments, it is desirable to reduce the temperature of the insulation while the wires are twinned.

In several examples, the relationship between exposure time to a cryogenic fluid, surface temperature, and compression ratio for both solid polymer and foamed polymer insulated conductors was further investigated. In the examples below, pairs of FEP insulated conductors were twinned together at a speed of 19 m/min after exposure to a cryogenic fluid. The surface temperature of the insulation was measured by direct contact with a temperature probe placed at the first contact point of the two insulated conductors.

Both foamed FEP insulation and solid FEP insulation conductors were exposed to cryogenic fluid (liquid nitrogen) for various lengths of time and their surface temperatures were measured. Table 5 shows the results of this example. Figure 9 shows a graph of these results.

[Table 5] - Surface temperature

Table 5 and Figure 9 show significant differences in the surface temperatures of the foam and solid polymer insulated conductors even when exposed to cryogenic fluids for the same period of time. After 6 seconds of exposure to liquid nitrogen, the foam insulated conductor maintained a much lower surface temperature than the solid polymer insulated conductor.

The surface temperature of the insulated conductor was measured approximately 1 second after the conductor was removed from the liquid nitrogen. Without being bound by theory, it is believed that the surface of the solid polymer insulation warms up more quickly than the surface of the foam insulation. The foam insulation comprises a number of closed air pockets. It is possible that the air trapped within these air pockets cools while the foam insulation wire is immersed in the liquid nitrogen, and that the cooled air then slows down the warming of the surrounding insulation. In other words, the cooled air pockets within the foam insulation may help maintain a lower surface temperature of the foam insulation compared to the solid polymer insulation. Over time, both the solid polymer insulation and the foam insulation will warm up to ambient temperature, but the foam insulation may remain at a significantly cooler temperature for a longer period of time.

In some embodiments, the cable is manufactured without significantly deforming the polymer cable components incorporated within the cable. Many polymer cable components have generally circular cross sections having many approximately equal diameters. Similarly, many polymer cable components' generally circular cross sections will all have many radii that are approximately equal to each other before the cable is compressed or deformed. To be clear, before the polymer cable component is compressed or deformed, the radius having the maximum length is approximately equal to the radius having the minimum length. While there is some natural variation in the wall thickness of the polymer cable component, the maximum and minimum radii are typically within 3% of each other. In some polymer cable components, the initial maximum and minimum radii may be within 5% of each other before being compressed or deformed.

In some embodiments, the generally circular cross-section of the polymer cable component is preserved after the polymer cable component is subjected to a compressive or deforming force. By increasing the hardness of the polymer cable component as described herein, the polymer component may deform less, thereby maintaining its generally circular cross-section. In some embodiments, after the polymer cable component is subjected to a compressive force, the maximum and minimum length radii are within about 10% of each other. In some embodiments, the maximum and minimum length radii are within about 8% or about 5% of each other. In some embodiments, the maximum and minimum length radii are within about 15% or about 12% of each other. It will be appreciated that the closer the maximum and minimum length radii are to each other, the closer the cross-section is to a circle, and the generally less the polymer cable component is deformed.

In some embodiments, by increasing the hardness of the polymer cable component by cooling the cable component for less than about 10 seconds, the polymer component may deform less after being subjected to a compressive or strain force. In some embodiments, after the polymer cable component is subjected to a compressive force, the maximum and minimum length diameters are within about 10% of each other. In some embodiments, the maximum and minimum length diameters are within about 8% or about 5% of each other. In some embodiments, the maximum and minimum length diameters are within about 15% or about 12% of each other. It will be appreciated that the closer the maximum and minimum length diameters are to each other, the closer the cross-section is to a circle and generally the less the polymer cable component will deform.

Twinning while the insulated conductor is still in a cooled state, and thus has a higher hardness, is one way to reduce the amount of strain during the twinning process. In some embodiments, this leads to a lower compression ratio and improved electrical properties of the final strand. In some embodiments, the time that the insulated conductor is exposed to the cryogenic fluid and/or the time that the cooled insulated conductor is exposed to ambient temperature before twinning may be adjusted to tailor the electrical properties of the final strand.

In some embodiments, the compression ratios and/or associated electrical characteristics of the individual conductors or strands may be adjusted to produce a plurality of strands having approximately the same propagation delay. In some embodiments, strands having a shorter twist length may be twinned while the individual insulated conductors are at a lower temperature to produce a strand having a reduced propagation delay relative to a strand having a longer twist length, and thus having a higher hardness. In some embodiments, strands having a longer twist length may be twinned while the individual insulated conductors are at a higher temperature relative to a strand having a shorter twist length, to produce a strand having a higher propagation delay relative to a strand having a shorter twist length. In some embodiments, the surface temperature of the insulated conductor forming the first strand may be adjusted relative to the surface temperature of the insulated conductor forming the second strand to produce first and second strands having propagation delays across 100 meters that are approximately the same, or propagation delays across 100 meters that are within 10 nanoseconds of each other, or propagation delays across 100 meters that are within 15 nanoseconds of each other, or propagation delays across 100 meters that are within 25 nanoseconds of each other, or propagation delays across 100 meters that are within 50 nanoseconds of each other. It will be appreciated that the surface temperature of the insulated conductor may be adjusted by adjusting the time interval that the insulated conductor is exposed to the cryogenic fluid, or by adjusting the time interval after the insulated conductor is removed from the cryogenic fluid but before the conductor is twinned or otherwise subjected to a compressive force. It will also be appreciated that other cooling methods other than exposure to the cryogenic fluid may be used as described herein. In all forms of cooling, the total degree of cooling can be controlled by controlling the temperature of the cooling material and/or the time that the polymer cable component is exposed to the cooling material. Similarly, regardless of the cooling method used, the temperature of the polymer cable component when subjected to a compressive or deforming force can be controlled by controlling the time that the polymer cable component is exposed to the ambient atmosphere after it has cooled and before it is subjected to the force.

In some embodiments, the first, second, third, and/or fourth pairs of polymer-insulated conductors, each pair including two polymer-insulated conductors, are temporarily cooled to slightly increase the hardness of each pair. In some embodiments, the degree of hardness increase may be different for each pair. Once the pair of polymer-insulated conductors are at the desired hardness, the pairs are twisted together to form first, second, third, and/or fourth strands. Each strand has a propagation delay over 100 meters. In some embodiments, the differences in the propagation delays over 100 meters for the first, second, third, and fourth propagation delays over 100 meters are within 50 nanoseconds of each other. In some embodiments, the propagation delays are all within 25 nanoseconds of each other. In some embodiments, the first, second, third, and fourth propagation delays over 100 meters have a delay skew of less than about 25 nanoseconds.

In some embodiments, the first, second, third, and/or fourth pairs of polymer insulating conductors are cooled for different time periods to individually reach a desired hardness for each pair. In some embodiments, the cooling periods are all less than about 20 seconds, or all less than about 15 seconds, or all less than about 10 seconds. In some embodiments, the first time period is about 8 to 10 seconds, the second time period is about 6 to 8 seconds, and the third time period is about 4 to 6 seconds. In some embodiments, the fourth time period is less than about 4 seconds and may be 0 seconds, indicating that one of the four pairs may not be significantly cooled at all.

In some embodiments, the duration of the cooling time and/or the degree of increase in hardness of the polymer insulated conductor is related to the expected twist length of the strand fabricated from that polymer insulated conductor. In general, the shorter the twist length, the longer the cooling time and/or the greater the increase in hardness prior to twinning relative to other pairs of conductors.

In some embodiments, the first, second, third and/or fourth strands have first, second, third and/or fourth twist lengths, respectively. The first twist length is shorter than the second twist length, and the second twist length is shorter than the third twist length. In some embodiments, the first cooling time period is longer than the second cooling time period, and the second cooling time period is longer than the third cooling time period.

In some embodiments, the first, second, third and/or fourth wires have first, second, third and/or fourth compression ratios, respectively. In some embodiments, the first compression ratio is less than the second compression ratio and the second compression ratio is less than the third compression ratio.

In some embodiments, the first, second, third and fourth wires have first, second, third and fourth signal rates, respectively. In some embodiments, the first signal rate is greater than the second signal rate, and the second signal rate is greater than the third signal rate.

In some embodiments, the first, second, third, and/or fourth pairs of polymer-insulated conductors each have a different increased hardness. In some embodiments, the increased hardness of the first pair of polymer-insulated conductors is greater than the increased hardness of the second pair of polymer-insulated conductors, and the increased hardness of the second pair of polymer-insulated conductors is greater than the increased hardness of the third pair of polymer-insulated conductors.

When two insulated conductors are twinned together, it will be appreciated that the generally circular cross-section of each of the insulated conductors will deform at least slightly. The closer the cross-section of each of the insulated conductors is to a circle, the greater the amount of air that is retained within the gap between the two insulated conductors. As more air is retained within the gap, the overall dielectric constant of the strand of conductors is reduced and the velocity of propagation is increased. By cooling the polymer insulated conductors and increasing their hardness while the conductors are twinned to form a strand, the polymer insulation is deformed less and a more circular cross-section is maintained. It will be appreciated that the dielectric constant of the insulating material itself is not increased or decreased. However, the dielectric constant of the resulting strand may be reduced as the insulating layer maintains its generally circular cross-section and incorporates a greater amount of air within the gap of the strand. In some embodiments, the purpose of cooling the polymer insulated conductors is to retain a greater amount of air within the gap of the resulting strand.

In some examples, the temperature of the conductor within the wire was analyzed both during and after exposure to a cryogenic fluid (liquid nitrogen). This analysis was based on the electrical resistance of the conductor using the mathematical equation shown below. Equation 1:

Here:

R = conductor resistance at temperature (T);

R _ref = conductor resistance at reference temperature (T _ref );

α = resistance coefficient of the conductive material at T _ref ;

T _ref = reference temperature (℃) at which α is specified for the conductive material;

T = conductor temperature (℃).

For example, α of copper at 20°C is known to be 0.00393 K ^-1 . R _ref was determined to be 1.25 ohm based on the calculations described below. To analyze the temperature of the conductor, the strand was connected to a portable cable analyzer which recorded the resistance of the conductor in real time. The insulated conductor was immersed in a liquid nitrogen bath and the resistance was recorded over time. Equation 1 (above) was then solved for T.

In this example, a 24'9" length of FEP insulated copper wire is used. The resistance of the 24'9" wire is known to be 1.51 ohms. The resistance of the 6" wire is known to be 0.26 ohms. To calculate the value of R _ref , the resistance of the 6" copper wire is subtracted from the resistance of the 24'9" copper wire to account for the approximate resistance of any other components in the circuit that are not the insulated conductors. Once R _ref is determined to be 1.25 ohms, equation 1 can be solved for T using the measured value of R.

The calculated temperature of the copper conductor over time is plotted in FIGS. 10 and 11. FIG. 10 shows more detail of the first 20 seconds after immersion of the conductor in liquid nitrogen. FIG. 11 shows the temperature of the conductor while immersed in the liquid nitrogen and likewise after being removed from the liquid nitrogen. The conductor was placed in the liquid nitrogen bath at time = 0. The conductor temperature decreased rapidly over the first 5 to 10 seconds before leveling off at about -176°C. The cable was allowed to remain in the liquid nitrogen bath for 120 seconds. When the conductor was removed from the liquid nitrogen bath at 120 seconds, the conductor temperature began to warm up again as shown in FIG. 11. Both the solid insulation and the foam insulation conductors reached about 0°C after about 40 seconds after being removed from the liquid nitrogen. As can be seen from FIGS. 10 and 11, the solid and foam insulating conductors were generally maintained at similar temperatures relative to each other when cooled in liquid nitrogen and when warmed after removal from the liquid nitrogen.

Although the disclosed invention has been generally described in terms of twinning wires, it is applicable to a wide variety of other applications.

In some embodiments, when two insulated conductors are brought together to form a stranded wire, additional tapes, fillers or hollow tubes may be added or incorporated into the stranded wire. In the case of tapes, these may be added between the insulated conductors, outside the stranded wire unit, and/or around the stranded wire unit.

FIG. 12 illustrates a schematic diagram of a twinning wire incorporating tapes according to one embodiment. As illustrated in FIG. 12, a tape (930) may be placed between two insulated conductors (920) of a twinning wire (910). The tape (930) is subjected to forces during the twisting of the twinning wire. As a result of these forces, the tape (930) may be compressed or otherwise deformed during the twinning process. Deformation of the tape (930) may lead to increased capacitance, increased insertion loss, decreased electrical impedance, and/or other undesirable effects on the electrical properties of the final twinning wire. By increasing the hardness of the tape (930) just prior to exposing the tape to the forces of the twinning process, the deformation of the tape may be reduced, and the electrical properties of the final twinning wire may be preserved or improved. As described elsewhere herein, the hardness of the tape may be increased by exposing the tape to a cryogenic fluid.

FIG. 13 schematically illustrates an embodiment in which a tape is wrapped around a strand. In some embodiments, one or more strands (1010) may be wrapped by a tape (1020). Each strand (1010) may include two conductors (1030) surrounded by an insulating layer (1040). In some cables, multiple strands (1010) are surrounded by a jacket (1050). The tape (1020) may be tightly formed around the strand (1010), thereby creating a strain, increasing capacitance, decreasing impedance, and/or increasing insertion loss. In some embodiments, the tape (1020) may include a combination of metal and polymeric insulating materials. As described, the polymeric material may be sensitive to compression or other forms of strain. In some embodiments, prior to wrapping the tape around the wire, the tape is passed through a cooling chamber where it is immersed, sprayed, or otherwise exposed to a cryogenic fluid or other cooling medium. By exposing the tape to the cryogenic fluid and increasing the hardness of the polymer, the tape may become stiffer and more resistant to deformation. It is contemplated that the amount of air between the layers of tape surrounding the wire and the wire may be increased by the higher stiffness (i.e., increased stiffness) of the tape. This is because a stiffer tape will not form itself as closely around the insulated conductor and will maintain a greater amount of air space within the interior of the tape wrap compared to a polymer tape having a lower hardness. Increasing the amount of air trapped between the tape and the wire will improve the electrical performance of the wire or the final cable. Air is a strong dielectric material. Increasing the amount of air within the cable or within the insulation generally has a positive effect on the electrical performance of the final wire and/or cable.

FIG. 14 schematically illustrates a cross-section of an embodiment in which hollow tubes are integrated into a twinning cable. FIG. 14 illustrates a cable comprising two conductors (1110) each surrounded by an insulation layer (1120). The insulated conductors are positioned within a jacket (1130). In some embodiments, the twinning may be combined with filler positioned within the gap between the hollow tubes (1140) and/or the two insulated conductors to create additional air space (1150) within the jacket (1130). These hollow tubes (1140) are typically made of a polymeric material and may be compressed or otherwise deformed as they are compressed against the insulated wires of the twinning process. As the hollow tubes or filler deform, the amount of air contained within the hollow tubes and/or contained within the jacket may be reduced. Additionally, as the hollow tube or filler deforms, the inter-pair spacing may be reduced or inconsistent, thereby increasing the amount of crosstalk between different pairs. In some cases, the reduced inter-pair spacing may also increase capacitance, increase insertion loss, decrease impedance, and/or otherwise degrade the electrical performance of the final cable.

By exposing the hollow tube (1140) or filler to the cryogenic fluid, the hardness of the hollow tube (1140) or filler is increased, making them more resistant to deformation and collapse into the gap of the pair, thereby maintaining the air space (1150) and improving electrical performance. The air pocket formed between the hollow tube (1140) and the gap of the pair aids in electrical performance. This is because the dielectric constant of air is 1.0, which is preferable to the dielectric constants of other materials such as FEP (2.0), polyethylene (2.3), and polyvinyl chloride (3.5). In some embodiments, maximizing the air content aids in wire and cable electrical performance.

FIG. 15 schematically illustrates cross-sections of embodiments in which protrusions are used to increase air space, reduce material cost, and/or reduce weight. In some embodiments, the jacket (1210), the cable (1220), and/or the hollow tube (1230) include protrusions (1240) or striations on the inner and/or outer surfaces to create additional air space (1250). In some embodiments, the protrusions (1240) and/or striations are sensitive to deformation. In such embodiments, increasing the stiffness of the hollow tube (1230) including the striations and/or protrusions (1240) to prevent deformation or collapse of the protrusions (1240) may help maintain and/or maximize the air space (1250) within the cable.

In some embodiments, a protrusion from the hollow tube, insulation layer, or jacket layer is formed during profile extrusion of the cable component. In some embodiments, the protrusion may be readily compressible or deformable. Hardening the surface by exposing the material to the cryogenic fluid may help reduce the effect of forces on the protrusion, thereby maintaining the amount of air that would otherwise be present if the protrusion were not compressible or deformable.

It will be appreciated that not only the polymer insulated wires may be exposed to cryogenic fluids, but also the hollow tubes, filler tubes, tapes, jackets, and/or other polymer cabling components may be exposed to cryogenic fluids or other cooling media to increase their hardness. By reducing the strain of the cable components, the air volume within the cable may be maintained or increased, and the electrical performance of the cable may be improved compared to a similar cable that is allowed to be compressed or deformed.

FIG. 16 schematically illustrates a cross-section of an embodiment in which a conductor is insulated by multiple layers of insulation. In some embodiments, multiple layers of different insulation materials may be used to surround the conductor. In some embodiments, an outer layer of material having a higher inherent hardness may be used to help reduce compression of a softer inner layer of material. In some embodiments, a foam insulation layer (1320) may be used to insulate the conductor (1310). Because the foam insulation contains many discrete air pockets, the hardness of the foam insulation layer may be significantly lower than a solid insulation layer of the same polymeric material. Accordingly, the foam insulation layer may be more sensitive to compression during manufacturing. An outer layer (1330) of a material having a higher hardness than the underlying foam insulation (1320) may be used to reduce compression of the foam insulation (1320). By exposing the insulating conductor (including the foam insulation and the outer jacket) to the cryogenic fluid, the hardness of the outer portion of the insulating material may be temporarily increased to reduce compression or deformation of the insulation during the manufacturing or cabling process. It will be appreciated that the overall thickness of the inner foam insulation layer may not need to be cooled to allow the outer portion of the foam insulation to have the temporarily increased hardness and resist compression during the cabling process. It will also be appreciated that the outer jacket (1330) may or may not be foam itself. In some embodiments, the jacket will be a solid polymer designed to protect the underlying foam insulation. In some embodiments, the outer jacket layer will comprise a different polymer than the foam insulation layer.

In some cable embodiments, separator tapes, cross webs, and/or star fillers are used between the stranded units to separate the stranded units from each other. Deformation of these separators may occur due to forces experienced during the cabling process, thereby reducing the air volume within the cable and negatively affecting the electrical performance of the cable.

FIG. 17 schematically illustrates a cross-section of an embodiment in which a plurality of strands are separated by cross webs. In the embodiment illustrated in FIG. 17, strands (1410) are separated from each other by polymer cross webs (1420). This reduces the amount of electromagnetic interference between strands (1420). The cross webs (1420) and strands are housed within a jacket (1430).

In some embodiments, the separator tape, cross web, and/or star filler are extruded polymer shapes without the benefit of a metal backing or rigid internal elements. The polymer separator may be manufactured from a high dielectric material (greater than 3.0). In some embodiments, the separator may be manufactured from a foam material, thereby improving its dielectric properties and also increasing its susceptibility to deformation. During the cabling process, the cable components are typically subjected to multiple compressive or strain forces. By exposing the separator tape, cross web, or star filler to a cryogenic fluid and temporarily increasing its hardness prior to or during the cabling process, the compression or strain of the separator or other components may be reduced, thereby increasing the air content within the cable and improving the electrical performance of the final cable.

In some embodiments, the polymer cable component may be cured prior to being compressed to reduce the degree of strain on the polymer cable component. In some embodiments, the polymer cable component may be cured prior to being compressed to allow the polymer cable component to withstand greater compressive forces while still being compressed to about the same degree as if the cable were not cured prior to being compressed.

In some embodiments, the first strand is manufactured by operating the twinning device or twinner at a first line speed. The resulting first strand has a particular first crimp ratio. Another strand can be manufactured by cooling the polymer insulated conductor to increase the hardness of the polymer insulation layer and then twinning the polymer insulated conductor by operating the cable twinning device at a second, faster speed to produce a second strand having a second crimp ratio. In some embodiments, the second strand is manufactured at the second, faster speed and has approximately the same crimp ratio as the first strand. In some embodiments, the second crimp ratio is within about 10 percent of the first crimp ratio. In some embodiments, the second crimp ratio is less than the first crimp ratio. In some embodiments, the second speed is at least about 15 percent faster than the first speed. In some embodiments, the second speed is at least about 25 percent faster than the first speed.

In some embodiments, the twinner or twinning device used will have a rated speed for a particular type of wire and cable product. In some embodiments, the first speed described above is the rated speed for the given twinner and cable product and the second speed is at least about 10% faster than the rated speed for the same product. In some embodiments, the first line speed is about 60 feet per minute and the second speed is about 70 feet per minute. In some embodiments, the first line speed is about 160 feet per minute and the second speed is about 180 feet per minute. In some embodiments, the first line speed is about 220 feet per minute and the second speed is about 275 feet per minute.

FIG. 18 schematically illustrates a cross-section of an embodiment in which a wire comprises a metal braid. In some embodiments, a conductor (1510) is insulated by a polymer insulation layer (1520) and a wire braid (1530) is formed over the insulation layer (1520). The wire braid (1530) may be made of a metal, such as copper, or may be plated with silver or tin. The wire braid (1530) may comprise a plurality of metal strands woven together. When the braid is applied to the polymer insulation layer (1520), the individual metal strands that make up the braid may create impressions on the surface and/or compress the polymer insulation layer (1520), thereby adversely affecting the electrical properties of the cable. In some embodiments, a plurality of polymer cable components, such as an insulated conductor and a hollow tube, are cabled together using a metal braid. In these embodiments, each polymer cable component in contact with the metal strands may be deformed by the compressive force of the metal strands, thereby negatively affecting the electrical properties of the final cable.

In some cases, the braid impressions on the polymer insulation layer are repeated at regular intervals. This can have a negative effect on periodic electrical signals that repeat at approximately the same regular interval or frequency or harmonics thereof. By increasing the hardness of the polymer insulation layer prior to applying the braid or metal strands, the impressions, compression and other deformations of the polymer insulation layer may be reduced.

In some embodiments, the cooling chamber, or other structure containing the cooling medium, positioned immediately prior to the braiding machine is less than about 5 feet long, or less than about 3 feet long, or less than about 1 foot long. Because of the relatively slow line speeds of most braiding machines, the footprint of the cooling chamber can be reduced without reducing the residence time of the polymer cable components within the cooling chamber.

In one non-limiting example, an uninsulated copper wire was used to simulate an impression formed in a polymer cable component during a metal braiding process. The metal braid is typically applied over a polymer cable component by weaving or braiding several individual metal strands together over the polymer component. As these individual strands are braided together, they compress and deform the polymer component underneath. To simulate this deformation process, a twinning machine was used to twin one conductor insulated with foam FEP and one uninsulated copper wire. Since the uninsulated copper wire was twisted around the foam FEP insulation, the impression left in the foam FEP insulation layer could be inspected. The bare copper wire was a 24 AWG wire and the FEP foam insulated conductor had an outside diameter of about 82.68 mils or about 2.1 mm.

The samples were produced using a tweener with a twist length of 6.2 mm and a twist rate of 1400 twists per minute and 30 feet per minute. The samples were collected as a control without the use of a cooling chamber after exposing the FEP foam insulation to liquid nitrogen for 10 seconds. The depth of the impression left by the copper wire on the foam insulation was analyzed using a laser microscope.

Upon initial visual inspection, the polymer insulation layer, which had not been exposed to liquid nitrogen, generally deformed into a helical shape when twinned with the bare copper wire. After 10 seconds of exposure to liquid nitrogen, which increased its hardness, the polymer insulation appeared generally straight with the copper wire wound in a helical shape around the straight foam insulation layer. The foam FEP insulation layer appeared unaltered by the twinning process with the bare copper wire.

The depth of the impression formed by the bare copper wire into the FEP foam insulation was measured three times at each of three locations: before the twiner take-up, inside the twiner bow, and on the twiner take-up reel. The data are presented in Table 6 below.

[Table 6] - Impression Depth

As the twinned pair moves from the coiling section, into the bow, and onto the coiling reel, the amount of force and the total number of compression events increase and the coiling length decreases. The distance and time elapsed since the polymer insulation leaves the cooling chamber also increases, which allows the polymer insulation to decrease in hardness as it returns to ambient temperature.

As can be seen in Table 6, at all locations, the samples exposed to liquid nitrogen for 10 seconds showed a significant reduction in the impression formed by the copper wire. Accordingly, it can be expected that if the polymer insulation layer is cured by cooling the polymer before applying the braid, the metal braid shielding layer applied on top of the polymer insulation layer will deform the polymer insulation layer less. Wire and cable products having a less deformed polymer insulation layer will generally have improved electrical properties compared to wire and cable products having a compressed or otherwise deformed polymer insulation layer.

In some embodiments, during the cabling process, when individual insulated conductors and/or other cable components are bundled together, compression and/or deformation may occur. Such deformation may result in compression of the insulation layer, compression of the insulated conductors into the cross web or other separator, and/or collapse of the jacketing layer. During the cabling process, twisting of the existing strands may increase the twist rate of the strands, thereby creating additional compressive forces within the existing strands. Stiffening the cable components by temporarily increasing their hardness during the cabling process may help reduce or avoid deformation of the various cable components individually or relative to one another. By exposing the cabling components to the cryogenic fluid prior to and/or during the cabling process, the desired arrangement of the cable may be maintained. Avoiding deformation maximizes the amount of air space within the cable and improves electrical performance. Allowing the physical arrangement of the cable to deform negatively affects the electrical performance of the cable.

As described herein, air is a desirable dielectric material, but air does not provide physical support to prevent conductors from contacting each other. Therefore, an insulator is utilized to prevent contact between conductors and reduce interference. To improve the electrical performance of the insulation, air may be introduced into the insulation via air channels (profile extrusion) or foaming (creating bubbles within the insulation material). Since air itself has no physical strength, introducing air into the insulation reduces the overall hardness of the insulation. A lower hardness results in greater compression or deformation as a result of the same external force. By exposing the insulation element to the cryogenic fluid and temporarily increasing the hardness of the insulation, the deformation created during the manufacturing process can be alleviated. In some embodiments, introducing air into the insulation allows the cryogenic fluid to cool the closed air pockets. This can help maintain the insulation at a reduced temperature for a longer period of time compared to a solid insulation without air pockets.

In some embodiments, by increasing the hardness of the polymer cable components prior to or during manufacturing, a lighter, smaller, and/or more usable cable may be produced. Less total insulation material may be required to achieve the same electrical performance if the cable components are not compressed or otherwise deformed. The total thickness of the insulation layer may also be reduced if the insulation layer is less compressed due to the increased hardness during manufacturing.

In some embodiments, the non-twisted wire may benefit from having a temporarily increased hardness of the polymer insulation layer. For example, the polymer insulation layer of a single polymer-insulated conductor may deform as the wire contacts rollers, guide bars, or other equipment during the manufacturing process. The polymer insulation layer may also deform when two wires are connected to form a non-stranded wire.

Many cables contain more than one strand. To reduce electrical interference between strands, each strand in the cable may have a different twist length or a different number of twists per meter. Differences in the twist lengths, as well as other differences in the strands, can result in a particular strand having a faster or slower signal speed. One factor that can result in a strand having a faster or slower signal speed is the amount of air in the gap between the two insulated conductors of the strand. The more the conductors in the strand are deformed by the compressive force of the twinning, the less air is retained in the gap. The less the conductors in the strand are deformed by the compressive force of the twinning, the more air is retained in the gap, the lower the dielectric constant of the strand, and the faster the signal speed of the strand. In addition to air being contained within the gap of the strand, air can also be contained between various components in the cable. In some cable embodiments, air pockets may be formed between the strands, between the strands and cross members, between the strands and filler tubes, and/or within the hollow tubes. Generally, the more air contained within a cable, the better the electrical properties of the cable.

In certain applications, data may be transmitted using multiple pairs of wires within a single cable. In order for that data to be properly processed, the data must be transmitted over the wires and received from each pair at specific times. In some embodiments, different twist lengths are used to reduce electrical noise between the different pairs. It is typical for four pairs to be used to transmit the signal. Using different twist lengths for each of these four pairs can allow the conductor path to be shorter or longer for one pair than for another. For example, a wire having a longer twist length and fewer twists per inch will have a shorter conductor path than a wire having a shorter twist length and more twists per inch.

In many applications, it is important that the signals on each pair of conductors arrive at approximately the same time. Different conductor lengths may cause the signals to arrive at different times. This can cause an effect called delay skew. In some embodiments, it is advantageous to accelerate the signal that would naturally arrive last (the longest conductor pair path) without slowing down or modulating the signal that arrives first (the shortest conductor pair path).

The difference between the signals received from the fastest and slowest signaling rates is called delay skew. It is desirable to have a delay skew of less than 25 ns. In some applications, a delay skew of less than 50 ns is acceptable.

As described, deformation of the polymer insulation layer within the strand can affect the electrical performance of the strand, including the signal speed. The tighter the twist, or the shorter the twist length of the strand, the greater the compressive force applied during twinning, and typically the greater the degree of deformation of the polymer insulation layer and the subsequent reduction in air dielectric between the insulating conductors.

In some embodiments, the plurality of strands will be exposed to the cryogenic fluid for different periods of time to adjust the signal speed and reduce the delay skew of the final cable. By exposing the polymer insulated conductor to the cryogenic fluid for different periods of time, a desired amount of deformation in the polymer layer may be introduced. By controlling the degree of polymer deformation, a desired amount of air within the strand gap may be controlled. While deformation generally has a negative effect on the electrical properties of the final strand, by being able to control the degree of the negative effect, the signal speed across the plurality of strands can be standardized and a cable having reduced delay skew across the plurality of strands can be produced.

In one non-limiting example, four strands are manufactured to be integrated into a single Ethernet cable. The polymer-insulated conductors forming each of the four strands are exposed to a cryogenic fluid prior to twinning. The polymer-insulated conductor forming the strand having the longest twist length may be exposed to the cryogenic fluid for, for example, about 2 seconds to reduce the degree of deformation of the polymer insulation layer. The polymer-insulated conductor forming the strand having the shortest twist length may be exposed to the cryogenic fluid for, for example, about 10 seconds to reduce the degree of deformation of the polymer insulation layer and preserve a greater portion of the air dielectric between the insulating conductors. The polymer-insulated conductors forming the strand having the more intermediate twist lengths may be exposed to the cryogenic fluid for periods of time ranging from 2 seconds to 10 seconds. By exposing the wires forming the different strands to the cryogenic fluid for different periods of time, the signal speed of the resulting strand can be adjusted and the delay skew of the resulting cable can be reduced.

While the dielectric constant of a given polymer may be known, the total amount of air space and insulating material surrounding the conductor within the strand is a function of the original polymer-insulated conductor, the degree of strain introduced by various cable components during cable design and manufacturing processes. In the case of a foamed polymer insulation, the amount of air space surrounding the conductor may be closely related to the degree of strain in the polymer insulation.

For a given conductor, the dielectric constant is inversely related to the propagation velocity. Accordingly, the time it takes for a signal to travel down a given length of wire is also related to the dielectric constant. The higher the total dielectric constant (the insulation layer combined with the air space) surrounding the conductor, the longer it will take for a signal to travel through the wire. By controlling the degree of deformation of various cable components, including, for example, the insulation layer, the wire, the hollow tube, the filler tube, and/or the jacketing, the electrical performance of the wire and/or cable can be adjusted. By combining a known or controlled signal velocity with the wire, a cable can be manufactured having reduced delay skew.

The propagation velocity along the wire can also be measured directly using commercially available equipment. The measured propagation velocity can be used to determine the combined dielectric constant (ε) using the following mathematical equation:

By directly measuring the propagation velocity, the combined dielectric constant (ε) can be calculated to take into account the dielectric effects of both the polymer insulation and the air space surrounding the conductor.

In one non-limiting example, if the propagation velocity of the strand is measured to be 68%. Based on the above equation, the combined dielectric constant is calculated to be 2.16. Also, using the time delay calculations provided above, the time delay of a signal traveling through this strand would be about 1.5 nanoseconds per foot. If the second strand is fabricated and the polymer insulated wires are exposed to the cryogenic fluid before being twinned together, the amount of air space surrounding the conductors may be increased, resulting in an improved propagation velocity. If the improved propagation velocity is 70%, with only a 2% increase, the final combined dielectric constant is calculated to be 2.04, and the calculated time delay is 1.45 ns/foot. Over a 330 foot strand length, a difference of 0.05 nanoseconds per foot between the two strands results in a total difference in signal delay of 16.5 nanoseconds. By exposing the polymer insulated conductors to the cryogenic fluid for a specified period of time, the combined dielectric constant and propagation velocity may be controlled. This allows the development of higher speed cables and also allows the creation of cables with reduced delay skew.

By exposing the polymer insulated conductor to a cryogenic fluid for varying periods of time, a desired amount of strain in the polymer layer can be introduced. The strain will generally have a negative effect on the electrical properties of the final strand, but by controlling the degree of the negative effect, signal speeds across multiple strands can be standardized, and cables with reduced delay skew can be produced.

In some embodiments, the tweener may be adjusted to run at faster or slower line speeds to control the amount of time the insulating conductor is exposed to the cryogenic fluid. In some embodiments, multiple cooling vessels of different lengths may be used to expose the polymer insulating conductor to the cryogenic fluid for different amounts of time. In some embodiments, a displacement block or adjustable baffle may be used to control the portion of the cooling vessel that actually contains the cryogenic fluid, thereby allowing a single cooling vessel to be used to expose the polymer to the cryogenic fluid for different amounts of time. By using a displacement block or adjustable baffle, a portion of the cooling vessel may be left without the cryogenic fluid, thereby creating a functionally variable length cooling vessel.

In some embodiments, one or more pulleys, wheels, capstans, and/or rollers may be used within the cooling vessel to redirect the path of the polymer cable component within the cooling vessel. This arrangement may allow the polymer cable component to remain within the cooling vessel for a longer period of time without increasing the length of the cooling vessel or reducing the line speed of the component. In some embodiments, the polymer cable component is redirected so that it enters the cooling vessel in the upper vapor region of the vessel where the evaporated cryogenic vapor rises above the cryogenic liquid, and then passes through the liquid region of the vessel where the liquid cryogenic fluid remains. This arrangement allows the polymer cable component to initially transfer heat to the cryogenic vapor prior to contacting the cryogenic liquid, thereby reducing the total heat load transferred to the cryogenic liquid and increasing the total residence time of the polymer cable component within the cooling vessel. In some embodiments, the redirecting wheel may be adjustable to control the total residence time of the polymer cable component within the cooling vessel.

It will be appreciated that the cable may be manufactured with one or more than one strand, including for example two, three, four, six or eight strands. Each strand within the cable may be exposed to the cryogenic fluid for a unique predetermined time to modulate the signal speed. By modulating the signal speed, the delay skew of the final cable may be reduced.

In some embodiments, the cable jacket is formed around the strand or other cable component using an extruder having a profile die. The cable component passes through the extruder die and the polymer is extruded around the cable component to form the jacket. In some embodiments, the cable jacket is exposed to a cryogenic fluid after being extruded around the cable component to avoid deformation of the cable jacket.

In some embodiments, the polymer may be exposed to the cryogenic fluid after being extruded to form a polymer shape, including but not limited to a hollow tube, a solid tube, a rectangular shape, an irregular shape, a shape having protrusions, indentations or cavities, or any other profile design. By exposing the extruded polymer shape to the cryogenic fluid after the shape has been extruded, the hardness of the extruded shape may be increased over a relatively short distance. In some embodiments, the exposure to the cryogenic fluid may be used to manipulate the crystalline structure of the extruded shape and/or to control the physical properties of the final polymer shape. In some embodiments, the extruded polymer may be exposed to a bath prior to being exposed to the cryogenic fluid. By exposing the extruded polymer shape to the cryogenic fluid, the final polymer may be easier to handle, mill, machine, or cut. The final polymer may be resistant to deformation and/or may produce less chips, dust, swarf, or unusable material during processing. In some embodiments, improved tensile and elongation properties may be achieved by adjusting the crystalline structure of the polymer cable components.

In some embodiments, the cryogenic cooling vessel may be integrated into an inline continuous or semi-continuous process. In some embodiments, the twinning machine may be configured to include a cryogenic cooling chamber before, during, and/or after the twinning machine twins the polymer insulated conductors to form a strand. In some embodiments, the cabling machine may be configured to include a cryogenic cooling chamber before, during, and/or after the cabling machine collects and/or twists cable components to form a cable core.

In some embodiments, the cryogenic cooling vessel comprises a vessel arranged to receive cryogenic liquid, a liquid level sensor, such as a float switch, an inlet arranged to provide cryogenic liquid, and/or an exhaust arranged to remove vaporized cryogenic fluid. In some cryogenic cooling vessels, the inlet is arranged to allow a polymer component, such as a polymer insulating conductor, to enter the cooling vessel and the outlet is arranged to allow the polymer component to exit the cooling vessel. In some embodiments, the inlet and outlet each have a diameter less than 0.3 mm larger than the diameter of the polymer sample. In some embodiments, the inlet and/or outlet are arranged in a profiled shape to accommodate a variety of profile polymer samples, such as cross webs. In some embodiments, the cooling vessel incorporates sensors and/or labeling devices to maintain consistent wire or cable quality during operation and/or line interruptions.

In some embodiments, the cooling vessel is arranged to expose the polymer insulated conductors to the cryogenic fluid prior to the first contact between the polymer insulated conductors. The first point of contact may be several feet before the polymer insulated conductors actually enter the twinning machine winding. A compressive force between the polymer insulated conductors at the first point of contact may be present, but may be weak compared to the peak compressive force that occurs when the polymer insulated conductors are twinned together. In some embodiments, the cooling vessel is arranged to expose the polymer insulated conductors to the cryogenic fluid after the first point of contact but before the polymer insulated conductors enter the twinning machine.

In some embodiments, the automated cryogenic exposure system may be utilized as part of an in-line continuous or semi-continuous process. The automated cryogenic exposure system may be utilized in conjunction with twinning lines, cabling lines, jacketing lines, and/or any other process in which polymeric materials may be compressed or deformed.

In some embodiments, the cryogenic exposure system includes a cold vessel having a variable length, a variable component path, a multi-component path, one or more sensors arranged to determine the diameter of the wire, strand, cable core or cable, and/or a machine automation controller.

In one non-limiting example, an optical sensor may be used to measure the diameter of one or two polymer insulated conductors that are unwound at the start of the twinning process. As described herein, the polymer insulated conductors may be passed through a cooling vessel containing a cryogenic fluid, such as liquid nitrogen, to increase the hardness of at least a portion of the polymer insulating layer. After passing through the cooling vessel, the two polymer insulated conductors are twisted together to form a twine. A second optical sensor may be used to measure the width of the resulting twine.

By measuring the diameters of the two polymer insulating conductors before they come into contact with each other, the two diameters can be combined to determine the potential width of the final twinned pair if the polymer insulating layers do not experience any compression or deformation. In some embodiments, the potential zero-strain width can also be determined by measuring the diameter of one of the polymer insulating conductors at the start of the twinning process and doubling it.

When measuring the width of the final strand, the optical sensor may also measure the width of the strand as it passes through a beam, such as a photon beam emitted by the optical sensor. It will be appreciated that the peak width measurement is used to represent the width of the strand when the individual conductors are oriented in a plane perpendicular to the beam of the optical sensor. When two conductors of the strand are laminated in line with the beam of the optical sensor, the measured width may be approximately equal to the width of one insulated conductor and does not represent the width of the strand. The measured width of the strand can be compared to a theoretical zero crimp width to determine the crimp ratio of the strand in real time.

As part of the twinning cable design, a desired compression ratio may be set to achieve the desired electrical characteristics. If the measured compression ratio is determined to be higher than the desired compression ratio setpoint, the cooling vessel may be adjusted to extend the length that the polymer insulated conductor is exposed to the cryogenic fluid during that time. By extending the length of the cooling vessel containing the cryogenic fluid, the exposure time of the polymer insulated conductor may be increased and the hardness of the polymer insulated conductor may be increased prior to exposure to the compressive forces of the twinning process. By increasing the hardness of the polymer insulated conductor prior to twinning, the compression ratio of the final strand may be decreased. In some embodiments, the twinner speed may be adjusted to help increase or decrease both the residence time of the insulated conductor in the cryogenic fluid and/or the compressive forces generated by the twinning process.

In some embodiments, the optical sensor and variable length cooling vessel may be coupled to one or more processors or machine automation controllers to create an automated quality control process. When the measured compression ratio deviates from a desired compression ratio setpoint, the controller may cause the variable length cooling vessel to respond by extending or contracting the length of the cooling vessel portion containing the cryogenic fluid and/or by adjusting the position of the redirecting wheel to extend or contract the length of the component path within the cooling vessel. By automatically adjusting the length of the cooling vessel portion containing the cryogenic fluid, the exposure time of the polymer insulating conductor to the cryogenic fluid, and thus the hardness of the polymer insulating layer, may be controlled. By adjusting the hardness of the polymer insulating layer, the compression ratio of the strand may be controlled.

In some embodiments, minor modifications to the variable length cooling vessel may occur on a continuous basis. Having granular and/or automated control over the length of the cooling vessel and thus the exposure time of the polymer insulated conductor to the cryogenic fluid allows the squeeze ratio to be controlled and maintained despite a wide variety of potentially complex factors including, but not limited to, ambient temperature, ambient sunlight, relative humidity, line speed, twist length, tweener parameters, tweener design, the type of polymer insulation used, whether the polymer insulation is foamed or solid, and/or the extent to which the polymer insulation is foamed, differences in the polymer insulated conductor from reel to reel, and many others.

In some embodiments, multiple cooling vessels may be used to control the total exposure time of the polymer insulating conductor to the cryogenic fluid. By using multiple individual cooling vessels, different methods of applying the cryogenic fluid to the polymer insulating material may be used on the same polymer insulating material. For example, a first cooling vessel may immerse the polymer conductor in a bath of cryogenic fluid, while a second cooling vessel may use a cryogenic fluid spray. It will be appreciated that any number of cooling vessels may be used in any of a number of configurations. By varying the configuration of some or all of the multiple cooling vessels, the exposure time of the polymer insulating conductor and the temperature of the polymer insulating conductor during twinning or other compressive stresses may be controlled in an adjustable manner.

Traditionally, obtaining the desired degree of crimp required a trial and error process in which a reel of stranded wire was manufactured and the electrical properties of the final reel were tested. If the electrical properties were not within predetermined specifications, the reel would be labeled as nonconforming and one of many variables would be changed. Another reel of stranded wire would then be manufactured and its electrical properties tested. This trial and error process was time consuming and resulted in material loss. Since the physical properties of polymer insulated conductors and the final stranded wire are known to affect the electrical properties, by controlling the degree of crimp of the stranded wire, the electrical properties of the stranded wire may also be controlled. The disclosed continuous and/or automated processes may be used to obtain the desired physical properties and therefore the desired electrical properties in less time and with less waste of material.

FIGS. 19A-19C illustrate schematic diagrams of a variable length cooling vessel according to one embodiment. As illustrated in FIG. 19A, the variable length cooling vessel may include a baffle (1630) arranged to move forward and backward to change the length of the cooling vessel containing the cryogenic fluid (1620). The baffle (1630) may be controlled by a motor (1650) connected to a threaded rod or screw drive (1660). As illustrated in FIG. 19A, the polymer insulating conductor (1610) may enter the cooling vessel through an aperture (1640). After passing through a portion of the cooling vessel that does not contain the cryogenic fluid (1620), the polymer insulating conductor may pass through the baffle (1630) through a similar aperture (1640). After passing through the baffle (1630), the polymer insulated conductor (1610) is exposed to the cryogenic fluid (1620). As illustrated in FIGS. 19b and 19c, the position of the baffle (1630) can be controlled using a motor (1650) and/or a screw drive (1660) to expand or contract a portion of the cooling vessel containing the cryogenic fluid (1620). By controlling the length of the portion of the cooling vessel containing the cryogenic fluid, the time that the polymer insulated conductor is exposed to the cryogenic fluid can also be controlled. By controlling the time that the polymer insulated conductor is exposed to the cryogenic fluid, the compression ratio and ultimately the electrical performance of the wire or cable can be controlled.

In some embodiments, a motor, screw drive, or other mechanism for controlling the position of the baffle in the variable length cooling vessel may be operatively connected to a machine controller. In some embodiments, the machine controller may be used to control the position of a redirecting wheel within the cooling vessel to adjust the length of the component path within the cooling vessel. This dynamic component path may be controlled to adjust the residence time of the polymer cable component within the cooling vessel. The machine controller may be in data communication with one or more processors that are in data communication with a first sensor for determining a diameter of the polymer insulated conductor and a second sensor for determining a width of the strand. The processor and the machine controller may compare the diameter of the polymer insulated conductor to the width of the final strand to determine a crimp ratio and compare the determined crimp ratio to a predetermined desired crimp ratio setpoint. The machine controller may then direct the motor and/or screw drive to adjust the exposure time of the polymer insulated conductor to the cryogenic fluid until the determined crimp ratio is approximately equal to the desired crimp ratio setpoint. Although the cryogenic exposure system described above is described in the context of a twinning system, it will be appreciated that the system may be applied to any other process in which the polymer component may be compressed or deformed.

In some embodiments, the cooling vessel comprises nozzles configured to spray the cryogenic fluid onto the polymer component. In some embodiments, rather than changing the physical size of the cooling chamber containing the cryogenic fluid, some of the plurality of nozzles may be closed, bypassed, or otherwise prevented from spraying the cryogenic fluid. This allows the exposure time of the polymer component to be controlled and allows the final compression ratio of the polymer component to be controlled as described above.

FIGS. 20A through 20C illustrate schematics of a variable spray cooling vessel according to one embodiment. As illustrated in FIG. 20A, a polymer insulating conductor (1710) may enter the cooling vessel through an aperture (1730). Cryogenic spray nozzles (1720) may be activated to expose the polymer insulating conductor (1710) to the cryogenic fluid. As illustrated in FIG. 20A, all of the plurality of spray nozzles (1720) may be activated to expose the polymer insulating conductor to a maximum amount of cryogenic fluid. As illustrated in FIG. 20B, some of the plurality of cryogenic spray nozzles (1720) may be deactivated to reduce the exposure time of the polymer insulating conductor to the cryogenic fluid. As illustrated in FIG. 20C, more spray nozzles (1720) may be deactivated to reduce the exposure time of the polymer insulating conductor to the cryogenic fluid. In some embodiments, the flow rate of the cryogenic fluid through one or more nozzles may also be adjusted to adjust the hardness of the polymer component passing through the cooling vessel. In some embodiments, all of the spray nozzles may be deactivated and the polymer component may not be exposed to the cryogenic fluid at all. By adjusting the flow of at least one of the plurality of cryogenic nozzles, the exposure time of the polymer insulating conductor to the cryogenic fluid may be adjusted. In some embodiments, the flow of the cryogenic fluid through the nozzles of the cooling vessel may be adjusted in response to the measured compression ratio to closely control the compression ratio of the strand or any other polymer component passing through the cooling vessel.

In some embodiments, reducing the compression or strain of polymer insulated conductors, cables, cable jackets, and other cable components allows these components to be manufactured using less polymer material while maintaining or improving electrical performance. By using less polymer material, the final cable has less combustible material and a lower fuel loading. Cables with a lower fuel loading are more likely to pass the UL 910 Steiner Tunnel test.

In some embodiments, the step of adding additional insulation and/or jacketing material to compensate for the expected deformation creates a new set of problems. For example, many cables must pass certain flame and smoke standards to ensure that the cable is safe for use in buildings or homes. One factor in the cable's tendency to propagate flame and generate smoke is the amount of material contained within it, commonly referred to as the "fuel load." Generally, as the amount of fuel (in this case, polymer insulation or jacketing material) is increased, the result is greater smoke generation or flame propagation from the cable under test.

An example of a fuel load test is the UL 910 Steiner Tunnel Test, which relates to ASTM E84, NFPA 255, UL 723, and ULC S102. In this test, a bundle of cables within a 24 ft x 1.8 ft x 1 ft noncombustible horizontal box or tunnel is subjected to a flame. The flame intensity is set to 89 kilowatts, and air is forced through the tunnel to simulate a plenum ceiling condition. Materials tested to these standards are required to exhibit a maximum flame spread distance of 5 ft, a maximum peak optical density of 0.5, and a maximum average optical density of 0.15.

Design engineers typically select materials that are optimized to meet cost and required fuel load standards. Potential problems arise when extra material is added to compensate for cable strain due to forces experienced during the manufacture of these cables. This extra material increases fuel load, increases cost, and limits the types of materials that can be employed. For example, some Category 6A cables offer shorter lay lengths that generate higher compressive forces during manufacture. These cables typically use FEP and PVC resins for insulation due to the higher than normal strain encountered during the manufacture of these products. Some other Category 6 cables utilize longer lay lengths and experience relatively reduced compressive forces during manufacture. Therefore, these cables require less additional insulation to compensate for strain. This lower fuel load allows for the use of other less expensive materials and/or

In some embodiments, the cable is manufactured by temporarily increasing the stiffness of the polymer cable components prior to or during the compression event. The increased stiffness reduces the degree of strain experienced during the compression event, and therefore requires less additional insulation material to achieve the desired electrical performance. In some embodiments, increasing the stiffness of the polymer cable components allows for a reduced total fuel load in the final cable, thereby allowing the cable to pass the UL 910 Steiner Tunnel Test, whereas a similar cable that does not experience the stiffness and stiffness increase and includes additional polymer material to compensate for the increased settlement would not pass the UL 910 Steiner Tunnel Test.

In some embodiments, cables having lower fuel loadings of more cost-effective materials may be developed that would not otherwise pass the UL 910 Steiner Tunnel Test without the reduced fuel loading. In some embodiments, cables manufactured using the disclosed techniques include reduced fuel loadings and are less likely to propagate flame or smoke.

In some embodiments, cables produced using the disclosed techniques may have a smaller outer diameter. This may allow existing buildings to be retrofitted with modern high-performance cables having the same or smaller diameter than previously used lower-performance cables.

In some embodiments, the wire and cable product has a specified amount of polymer insulation and/or other polymer cable components contributing to its fuel load. In some embodiments, the fuel load is designed to produce a flame travel distance of less than or equal to about 5 feet, a peak optical density of smoke of less than or equal to about 0.5, and/or an average optical density of smoke of less than or equal to about 0.15, as measured according to the Steiner Tunnel Test Method of ASTM E84, such as those described in ASTM E84, UL910, NFPA 255, UL 723, or ULC S102.

In some embodiments, the polymer cable component is cooled and/or cured prior to undergoing the compression event. Due to the curing, the polymer cable component may provide the desired electrical properties because it is not deformed as much as would occur if the polymer cable component were not cooled and/or cured prior to compression.

In some embodiments, because the polymer cable components are less deformable after curing, less total polymer may be included in the wire and cable product, thereby reducing the total fuel load of the wire and cable product. In some embodiments, the reduced fuel load wire and cable product has a capacitance value less than about 20 pf/ft. In some embodiments, the reduced fuel load wire and cable product has an impedance value equal to about 50 ohms to 150 ohms, or about 75 ohms to 125 ohms, or about 100 ohms. In some embodiments, the reduced fuel load wire and cable product has a propagation velocity of about 62% to 80%, or about 66% to 70%.

In some manufacturing facilities, there is sufficient space to allow the very hot insulated conductor or other polymer cable component to cool slowly after it has been extruded. In some facilities, this initial cooling step involves exposing the recently extruded polymer component to ambient air or to water contained in a trough for an extended period of time. Since wire and cable manufacturing is typically a continuous process in which the cable component moves rapidly, each of these cooling methods can require a significant amount of space, for example, in excess of about 40 feet. The long distances required to allow the extruded polymer component to cool require significant manufacturing floor space. Additionally, these cooling methods typically do not bring the temperature of the polymer cable component below ambient temperature.

In some embodiments, a faster temperature reduction is advantageous both for saving time and for reducing the footprint of the extruder manufacturing operation. In some embodiments, a cooling chamber having a cooled or cryogenic fluid can be used to rapidly cool the polymer cable component immediately after extrusion. In some embodiments, the cooling chamber after the extruder is less than about 10 feet long, or less than about 8 feet long, or less than about 5 feet long, or less than about 3 feet long.

In one non-limiting example, the Shore D hardness of solid FEP plaques was measured as described below. Injection molded plaques of solid FEP polymer were used throughout this example. The plaques were 61 mm long, 61 mm wide, and 2 mm high. The Shore D hardness of the solid FEP plaques was measured at an ambient temperature of about 20° C. The plaques were then exposed to liquid nitrogen for different lengths of time by immersing the plaques in a pool of liquid nitrogen. The Shore D hardness of the plaques was measured after different exposure times. The data are shown in FIG. 21 .

As can be seen in Figure 21, the Shore D hardness of the FEP plaque increases from about 60 to about 83 after exposure to liquid nitrogen for about 10 seconds. After about 10 seconds of exposure to liquid nitrogen, the FEP plaque reached a maximum hardness of about 83. Continued exposure to liquid nitrogen beyond 10 seconds did not continue to increase the hardness of the FEP plaque.

In subsequent examples, the Shore D hardness of solid FEP plaques was measured as the plaques were exposed to liquid nitrogen for specified periods of time and then returned to ambient temperature. The plaques were immersed in liquid nitrogen for 6, 10, or 30 seconds and then removed from the liquid nitrogen. For each of the three tests, the Shore D hardness of the plaques was measured at specified time intervals until the plaques returned to ambient temperature.

Figure 22 illustrates the Shore D hardness of plaques upon return to ambient temperature after immersion in liquid nitrogen for 6, 10, or 30 seconds. As shown in Figure 22, there is relatively little difference in hardness change over time between the samples exposed to liquid nitrogen for 10 seconds and those exposed to liquid nitrogen for 30 seconds. This suggests, in correlation with the data shown in Figure 21, that the FEP plaques reached their maximum hardness after about 10 seconds of exposure to liquid nitrogen. It is likely that the plaques exposed to liquid nitrogen for 6 seconds reached a lower initial Shore D hardness of about 76, which decreased as the plaques were exposed to ambient conditions.

In a follow-up example, a solid FEP plaque was immersed in liquid nitrogen for 10 seconds and then removed. The Shore D hardness and the temperature (in °C) of the plaque were measured when the plaque was returned to ambient temperature. Figures 23a through 23c illustrate this data over different time periods.

Figure 23a illustrates the Shore D hardness drop and temperature rise of a solid FEP plaque over a period of about 390 seconds. Figure 23b illustrates the Shore D hardness drop and temperature rise of a solid FEP plaque over a period of about 180 seconds. Figure 23c illustrates the Shore D hardness drop and temperature rise of a solid FEP plaque over a period of about 30 seconds. It should be noted that the temperature data below -60° C. in Figures 23a-23c are estimates rather than direct measurements.

In another non-limiting example, the Shore D hardness of foam FEP was measured. To prepare the foam FEP samples, the FEP foam insulated wire was tightly wound around a solid FEP plaque. The Shore D hardness of the foam FEP insulated wire was measured at an ambient temperature of about 20°C. The FEP foam insulated wire was then exposed to liquid nitrogen for different lengths of time by immersing the FEP foam insulated wire in a pool of liquid nitrogen. The Shore D hardness of the foam FEP was measured after different exposure times. The data are shown in FIG. 24.

As illustrated in FIG. 24, the Shore D hardness of the FEP foam is about 29 at ambient temperature and increases to about 63 after exposure to liquid nitrogen for about 15 seconds. Once the foam FEP reaches a Shore D hardness of about 63, the Shore D hardness plateaus and does not increase significantly after additional exposure time to liquid nitrogen.

Figure 25 shows the Shore D hardness of FEP foam insulated wire when returned to ambient temperature after being immersed in liquid nitrogen for 10 seconds. As the foam FEP is exposed to ambient temperature for longer periods of time, the Shore D hardness decreases until it reaches a Shore D hardness of about 29 at ambient temperature.

In a follow-up example, the foam FEP insulated wire was immersed in liquid nitrogen for 10 seconds and then removed. The Shore D hardness and temperature of the foam FEP insulated wire were measured as the foam FEP returned to ambient temperature. Figure 26 illustrates this data over a period of time.

Figure 26 illustrates the Shore D hardness decay and temperature rise of a solid FEP plaque over a period of approximately 390 seconds. It should be noted that no initial temperature data were collected below approximately -55°C.

Figure 27 shows the Shore D hardness of both solid FEP and foam FEP when exposed to liquid nitrogen over time. As can be seen from Figure 27, the Shore D hardness for solid FEP typically stops increasing after about 10 seconds. The Shore D hardness for foam FEP typically stops increasing after about 15 seconds.

Figure 28 shows the Shore D hardness of both solid FEP and foam FEP when exposed to liquid nitrogen for 10 seconds and then exposed to ambient conditions. In particular, the Shore D hardness of the foam FEP decreased more slowly and took over 3 minutes longer than the solid FEP to return to its Shore D hardness at ambient temperature.

Figure 29 shows the temperatures of solid FEP and foam FEP when exposed to liquid nitrogen for 10 seconds and then exposed to ambient conditions. The temperature of the foam FEP increased more slowly and took over 10 minutes longer to return to ambient temperature than the solid FEP.

Without being bound by theory, it is believed that air pockets within the foam FEP change temperature more slowly than solid FEP. Accordingly, the foam FEP insulation takes longer to reach its minimum temperature and associated increased hardness when exposed to liquid nitrogen. The foam FEP also takes longer to return to its ambient temperature and associated hardness after being removed from the liquid nitrogen.

While the above examples have been described in terms of solid and foam FEP, it will be appreciated that similar data may be readily collected for any shape and type of polymer. Once the rate at which the hardness of the polymer returns to ambient hardness is understood, the hardness of the polymer cable component when subjected to a compression event can be controlled by controlling the time that the polymer component is exposed to ambient temperature after leaving the cooling vessel. In some embodiments, the distance between cooling vessels and/or the line speed of the manufacturing line may also be adjusted to achieve the desired hardness of the polymer cable component at the compression or strain point.

It will likewise be appreciated that the cooling time (e.g., exposure time to a cryogenic fluid or other cooling medium) may alternatively or additionally be adjusted to reach a desired hardness of the polymer cable component at the point where it is subjected to a compressive or other deforming force.

In some embodiments, the method described herein for increasing hardness results in an increase in the Shore D hardness of the polymer cable component by at least about 10% before the component experiences a compressive force or when the polymer cable component experiences a compressive force relative to a similar component at ambient temperature.

In some embodiments, the method for increasing hardness described herein produces an increase in Shore D hardness in a polymeric cable component of at least about 10 percent or greater as compared to a similar component made from the same polymer at 20° C. In some embodiments, the method for increasing hardness described herein produces an increase in Shore D hardness in a polymeric cable component of at least about 10 percent or greater as compared to a similar component at 20° C. and reduces strain caused by a compression event by at least about 0.0005 inches.

In some embodiments, an increase in Shore D hardness of at least about 10% compared to a similar component at ambient temperature is achieved using a cooling chamber that is less than about 10 feet long.

In all cases, it can be understood that a 10% increase in Shore D hardness can be converted to other hardness tests such as other Shore hardness scales such as Brinell, Meyer, Vickers, Rockwell, and Shore A.

For reference, the Shore D durometer test is described in ASTM D2240 and ISO 868. Hardness values are determined by penetration of the durometer indenter foot into the sample. Shore hardness measurements are dimensionless and range from 0 to 100. The higher the Shore hardness number, the harder and more resistant to deformation the material. In some embodiments, the disclosed methods for increasing hardness are most advantageous for substrates exhibiting Shore hardnesses of 40 to 80.

The methods, systems and embodiments described herein generally relate to adjusting the hardness of polymer components. Polymers contemplated herein include, but are not limited to, thermoplastics, thermosets, rubbers and/or elastomers, each of which may be foamed or solid and may contain various additives and/or flame retardants. Specific polymers considered include linear low-density polyethylene-LLDPE, high-density polyethylene-HDPE, polyethylene-PE, perfluoroalkoxy alkanes-PFA, polytetrafluoroethylene-PTFE, polyvinylidene fluoride-PVDF, ethylene chlorotrifluoroethylene-ECTFE, tetrafluoroethylene perfluoromethylvinyl ether-MFA, polyphenylene sulfide-PPS, polyether ether ketone-PEEK, polyether ketone-PEK, polyethylene imine-PEI, fluorinated ethylene propylene-FEP, ethylene tetrafluoroethylene-ETFE, ethylene fluoroethylene propylene-EFEP, polypropylene-PP, nylon-PA, polyvinyl chloride-PVC, polycarbonate-PC, acrylonitrile butadiene styrene-ABS, polystyrene-PS, polyesters such as polyethylene terephthalate (PET), polyimides-PI, polyamide-imides-PAI, natural rubber, synthetics. Including but not limited to rubber, fluoroelastomers-FKM and blends or alloys thereof.

The disclosed embodiments include a method of reducing the effect of a compressive force on a polymer cable component, the method comprising: providing a polymer cable component having a first hardness, which is a hardness of the polymer cable component under ambient conditions; temporarily changing the hardness of the polymer cable component to a second hardness, which is different from the first hardness; applying a compressive force to the polymer cable component; and allowing the polymer cable component to return to the first hardness. In some embodiments, the polymer cable component is subjected to the compressive force while the polymer cable component is at the second hardness. In some embodiments, the compressive force produces less deformation of the polymer cable component at the second hardness compared to the polymer cable component at the first hardness. In some embodiments, the second hardness is greater than the first hardness. In some embodiments, the step of temporarily changing the hardness of the polymer cable component comprises cooling the polymer cable component. In some embodiments, the step of cooling the polymer cable component comprises exposing the polymer cable component to a cooled fluid. In some embodiments, the step of cooling the polymer cable component comprises exposing the polymer cable component to a cooled solid surface. In some embodiments, the cooled solid surface rotates. In some embodiments, the step of cooling the polymer cable component comprises exposing the polymer cable component to a cryogenic liquid. In some embodiments, the polymer cable component is exposed to the cryogenic liquid for less than about 10 seconds. In some embodiments, the polymer cable component is exposed to the cryogenic liquid for between 6 seconds and 10 seconds. In some embodiments, the step of cooling the polymer cable component comprises exposing the polymer cable component to a cooled gas. In some embodiments, the cooled gas is between 15° C. and -10° C. In some embodiments, the polymer cable component comprises an outer surface, an inner bulk, and an inner surface, and the step of cooling the polymer cable component comprises cooling the outer surface of the polymer cable component. In some embodiments, the polymer cable component is a polymer insulation surrounding the circumference of the conductor. In some embodiments, the polymer cable component is a fluoropolymer insulation surrounding the circumference of the conductor. In some embodiments, the polymer cable component is not cooled for less than 10 seconds before the polymer cable component is subjected to a compressive force. Some embodiments further comprise stopping the cooling of the polymer cable component less than 5 seconds before the polymer cable component is subjected to a compressive force.

Additional disclosed embodiments include a method of making a communication cable, the method comprising the steps of: providing a polymer cable component having a first cross-sectional radius and a second cross-sectional radius, wherein the first cross-sectional radius is a maximum distance from a center of the polymer cable component to an edge of the polymer cable component along the cross-section, and the second cross-sectional radius is a minimum distance from a center of the polymer cable component to an edge of the polymer cable component along the cross-section, the first cross-sectional radius is approximately equal to +/- 3% of the second cross-sectional radius, the polymer cable component having a first hardness, the first hardness being a hardness of the polymer cable component under ambient conditions; temporarily changing the hardness of the polymer cable component to a second hardness greater than the first hardness; applying a compressive force to the polymer cable component, wherein after the compressive force, the first cross-sectional radius is approximately equal to +/- 10% of the second cross-sectional radius. In some embodiments, the compressive force produces less deformation of the polymer cable component at the second hardness than the polymer cable component at the first hardness. In some embodiments, the step of temporarily changing the hardness of the polymer cable component comprises cooling the polymer cable component. In some embodiments, the step of cooling the polymer cable component comprises exposing the polymer cable component to a cooled fluid. In some embodiments, the step of cooling the polymer cable component comprises exposing the polymer cable component to a cryogenic liquid. In some embodiments, the step of cooling the polymer cable component comprises exposing the polymer cable component to a cooled gas. In some embodiments, the polymer cable component is not cooled for more than 10 seconds before the compressive force is applied. Some embodiments further comprise ceasing the cooling of the polymer cable component for less than 5 seconds before the polymer cable component is subjected to the compressive force. In some embodiments, the polymer cable component is a polymer insulation surrounding the circumference of the conductor. In some embodiments, the polymer cable component is a fluoropolymer insulation surrounding the circumference of the conductor. A further disclosed embodiment comprises a method of making a communication cable, the method comprising: providing a polymer cable component having a first diameter and a second diameter, wherein the first diameter and the second diameter are perpendicular to one another, the first diameter is approximately equal to +/- 3% of the second diameter, the polymer cable component having a first hardness, the first hardness being a hardness of the polymer cable component under ambient conditions; temporarily changing the hardness of the polymer cable component to a second hardness greater than the first hardness; applying a compressive force to the polymer cable component, wherein after the compressive force, the first diameter is approximately equal to +/- 10% of the second diameter; allowing the polymer cable component to return to the first hardness. In some embodiments, the polymer cable component is subjected to the compressive force while the polymer cable component is at the second hardness. In some embodiments, the compressive force produces less deformation of the polymer cable component at the second hardness than the polymer cable component at the first hardness. In some embodiments, the second hardness is greater than the first hardness. In some embodiments, the step of temporarily changing the hardness of the polymer cable component comprises cooling the polymer cable component. In some embodiments, the step of cooling the polymer cable component comprises exposing the polymer cable component to a cooled solid surface. In some embodiments, the cooled solid surface is rotated. In some embodiments, the step of cooling the polymer cable component comprises exposing the polymer cable component to a cryogenic liquid. In some embodiments, the step of cooling the polymer cable component comprises exposing the polymer cable component to a cooled gas. In some embodiments, the cooled gas is between 15° C. and -10° C.

A further disclosed embodiment comprises a method of making a communications cable, the method comprising the steps of providing first, second, third and fourth pairs of polymer-insulated conductors, each pair of polymer-insulated conductors comprising two polymer-insulated conductors, each polymer-insulated conductor having a first hardness, wherein the first hardness is a hardness of the polymer-insulated conductors at ambient conditions; temporarily changing the hardness of the polymer-insulated conductors of the first, second and third pairs of polymer-insulated conductors to a second hardness different from the first hardness; twisting the first pair of polymer-insulated conductors together to form a first strand having a first propagation delay over 100 meters; twisting the second pair of polymer-insulated conductors together to form a second strand having a second propagation delay over 100 meters; twisting the third pair of polymer-insulated conductors together to form a third strand having a third propagation delay over 100 meters; A fourth strand having a fourth propagation delay over 100 meters comprises a step of twisting together a fourth pair of polymer-insulated conductors to form a fourth strand, wherein the differences in the propagation delay over 100 meters for the first, second, third, and fourth propagation delays over 100 meters are within 50 nanoseconds of each other. In some embodiments, the first, second, third, and fourth propagation delays over 100 meters have a delay skew of less than about 25 nanoseconds. In some embodiments, the step of temporarily modifying the hardness of the polymer-insulated conductor comprises cooling the polymer-insulated conductor. In some embodiments, the step of temporarily modifying the hardness of the polymer-insulated conductor of the first, second, third, and fourth pairs of polymer-insulated conductors comprises cooling the first, second, third, and fourth pairs of polymer-insulated conductors for first, second, third, and fourth time periods, respectively. In some embodiments, the first time period is longer than the second time period, and the second time period is longer than the third time period. In some embodiments, the first time period is about 8 to 10 seconds, the second time period is about 6 to 8 seconds, and the third time period is about 4 to 6 seconds. In some embodiments, the first, second, third, and fourth stranded conductors have first, second, third, and fourth twist lengths, respectively, wherein the first twist length is shorter than the second twist length and the second twist length is shorter than the third twist length. In some embodiments, the first, second, third, and fourth stranded conductors have first, second, third, and fourth twist lengths, respectively, wherein the first twist length is shorter than the second twist length and the second twist length is shorter than the third twist length, the first time period is longer than the second time period, and the second time period is longer than the third time period. In some embodiments, the polymer insulated conductors of the first, second, third, and fourth stranded conductors have first, second, third, and fourth compression ratios, respectively. In some embodiments, the first compression ratio is less than the second compression ratio, and the second compression ratio is less than the third compression ratio. In some embodiments, the first, second, third, and fourth strands have first, second, third, and fourth signal rates, respectively. In some embodiments, the first signal rate is greater than the second signal rate, and the second signal rate is greater than the third signal rate. In some embodiments, the first, second, third, and fourth pairs of polymer-insulated conductors each have different second hardnesses. In some embodiments, the second hardness of the first pair of polymer-insulated conductors is greater than the second hardness of the second pair of polymer-insulated conductors, and the second hardness of the second pair of polymer-insulated conductors is greater than the second hardness of the third pair of polymer-insulated conductors. A further embodiment relates to a method of making a communications cable, the method comprising the steps of providing a first pair of polymer-insulated conductors and a second pair of polymer-insulated conductors, each pair of polymer-insulated conductors comprising two polymer-insulated conductors, each polymer-insulated conductor having a first hardness, wherein the first hardness is a hardness of the polymer-insulated conductors at ambient conditions; temporarily changing the hardness of the polymer-insulated conductors of the first pair of polymer-insulated conductors to a second hardness different from the first hardness; twisting the first pair of polymer-insulated conductors together to form a first strand having a first propagation delay over 100 meters; and twisting the second pair of polymer-insulated conductors together to form a second strand having a second propagation delay over 100 meters, wherein the first propagation delay over 100 meters and the second propagation delay over 100 meters are within 25 nanoseconds of each other. In some embodiments, the step of temporarily changing the hardness of the polymer insulating conductors of the first and second pairs of polymer insulating conductors comprises the step of cooling the first and second pairs of polymer insulating conductors.

Some disclosed embodiments relate to systems for manufacturing wire and cable products, the system comprising: an unwinder configured to unwind a polymer cable component; a cooling vessel configured to receive the polymer cable component, the cooling vessel containing a cooled fluid; and a winder configured to wind the polymer cable component. In some embodiments, the cooling vessel contains liquid nitrogen. In some embodiments, the cooling vessel further comprises a secondary structure configured to receive the polymer cable component, the interior of the secondary structure being in fluid communication with the interior of the cooling chamber. In some embodiments, the cooling vessel contains liquid nitrogen, and the nitrogen vapor travels from the interior of the cooling vessel to the interior of the secondary structure. In some embodiments, the secondary structure is a hollow tube. In some embodiments, the atmosphere within the cooling vessel is lower than the ambient temperature. In some embodiments, the cooling vessel is insulated. In some embodiments, the cooling vessel further comprises refrigeration equipment, the refrigeration equipment being configured to provide cooled air to the cooling vessel. In some embodiments, the polymer cable component is a polymer insulated conductor, and further comprises a twiner configured to receive a first polymer insulated conductor and a second polymer insulated conductor and form a strand. In some embodiments, the atmosphere within the twinner is lower than the ambient temperature. Some embodiments further include a secondary structure configured to receive a polymer cable component, the interior of the secondary structure being in fluid communication with the interior of the cooling chamber, the secondary structure being in fluid communication with the interior of the twinner. A further embodiment relates to a system for manufacturing a wire and cable product, the system including an unwinder configured to unwind a polymer cable component; a cooling surface configured to contact the polymer cable component; and a winder configured to wind the polymer cable component. In some embodiments, the cooling surface is a cooled roller. Some embodiments further include a plurality of cooled rollers.

Another disclosed embodiment is directed to a method of making a low fuel load wire and cable product, the method comprising the steps of: establishing desired electrical characteristics of the wire and cable product, wherein the wire and cable product comprises a polymeric cable component, the polymeric cable component having a first fuel load and a first hardness, wherein the polymeric cable component has a flame travel distance of less than or equal to about 5 feet, a peak optical density of smoke of less than or equal to about 0.5, and an average optical density of smoke of less than or equal to about 0.15 as measured in accordance with the Steiner Tunnel Test Method of ASTM E84, wherein the first hardness is a hardness of the polymeric cable component under ambient conditions; temporarily changing the hardness of the polymeric cable component to a second hardness that is greater than the first hardness; applying a compressive force to the polymeric cable component while the polymeric cable component is at the second hardness, thereby causing a first amount of strain in the polymeric cable component; and forming a wire and cable product using the polymer cable component, wherein the wire and cable product satisfies the set desired electrical properties when the polymer cable component is deformed to a first strain but does not satisfy the desired electrical properties when the polymer cable component is deformed to a second strain, wherein the second strain is an amount by which the polymer cable component would be deformed when subjected to a compressive force when the polymer cable component is at the first hardness. In some embodiments, the polymer cable component is a polymer insulation layer around a conductive wire. In some embodiments, the wire and cable product is a stranded wire. In some embodiments, the wire and cable product produces a flame travel distance of less than 4 feet as measured by the Steiner Tunnel Test Method set forth in ASTM E84. In some embodiments, the wire and cable product produces a peak optical density of smoke of less than 0.4 as measured by the Steiner Tunnel Test Method set forth in ASTM E84. In some embodiments, the wire and cable product produces an average optical density of less than 0.15 as measured by the Steiner Tunnel Test Method set forth in ASTM E84. In some embodiments, the desired electrical characteristics of the wire and cable product are a capacitance value of less than about 20 pf/ft. In some embodiments, the desired electrical characteristics of the wire and cable product are an impedance value of about 75 ohms to 125 ohms. In some embodiments, the desired electrical characteristics of the wire and cable product are a propagation velocity of about 62% to 80%.

A further disclosed embodiment relates to a method of forming a strand, comprising: operating a cable twinning apparatus at a first speed to produce a first strand having a first crimp ratio; providing a first polymer insulated conductor comprising a first conductor electrically insulated by a first polymer insulating layer; providing a second polymer insulated conductor comprising a second conductor electrically insulated by a second polymer insulating layer; exposing at least the first polymer insulated conductor to a cryogenic fluid; and operating the cable twinning apparatus at a second speed to produce a second strand having a second crimp ratio, the second strand comprising the first and second polymer insulated conductors, wherein the second speed is greater than the first speed. In some embodiments, the second crimp ratio is within 10% of the first crimp ratio. In some embodiments, the second crimp ratio is less than the first crimp ratio. In some embodiments, the second speed is at least 15% greater than the first speed. In some embodiments, the second speed is at least 25% greater than the first speed. In some embodiments, the first speed is a rated speed of the cable twinning device for wire and cable products, and the second speed is at least 10 percent faster than the first speed. In some embodiments, the second speed is at least 10 percent faster than the first speed, and the second compression ratio is less than the first compression ratio. In some embodiments, the first speed is at least 60 feet per minute and the second speed is at least 70 feet per minute. In some embodiments, the first speed is at least 160 feet per minute and the second speed is at least 180 feet per minute. In some embodiments, the first speed is at least 220 feet per minute and the second speed is at least 275 feet per minute. In some embodiments, the cryogenic fluid is liquid nitrogen.

Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow. It should be understood that any given element of the disclosed embodiments of the present invention may be implemented as a single structure, a single step, a single material, etc. Similarly, a given element of the disclosed embodiments may be implemented as a plurality of structures, steps, materials, etc.

The foregoing description illustrates and describes the processes, machines, manufactures, compositions of matter, and other teachings of the present disclosure. Additionally, while the present disclosure illustrates and describes only specific embodiments of the disclosed processes, machines, manufactures, compositions of matter, and other teachings, it should be understood that the teachings of the present disclosure are capable of use in various other combinations, modifications, and environments and that changes or modifications are possible within the scope of the teachings as expressed herein, commensurate with the skill and/or knowledge of those skilled in the art. The embodiments described herein above also illustrate certain best modes known to practice the processes, machines, manufactures, compositions of matter, and other teachings of the present disclosure and are intended to enable one of ordinary skill in the art to utilize the teachings of the present disclosure in these or other embodiments and with various modifications as required by a particular application or use. Accordingly, the processes, machines, manufactures, compositions of matter, and other teachings of the present disclosure are not intended to be limited to the precise embodiments and examples disclosed herein. Any section headings herein are intended to be limited to the specific embodiments and examples set forth herein, as defined in 37 C.F.R. Provided solely for consistency with the suggestions in § 1.77 or otherwise to provide organizing cues. These headings are not intended to limit or characterize the invention(s) described herein.

Claims (88)

A method for reducing the effect of compressive force on polymer cable components,
A step of providing a polymer cable component having a first hardness, which is a hardness of the polymer cable component under ambient conditions;
A step of temporarily changing the hardness of a polymer cable component to a second hardness different from the first hardness;
A step of applying a compressive force to a polymer cable component;
A step for allowing the polymer cable component to return to the first hardness,
The step of temporarily changing the hardness of the polymer cable component comprises the step of cooling the polymer cable component;
The step of cooling the polymer cable component comprises exposing the polymer cable component to a cryogenic liquid;
A method wherein the polymer cable component is exposed to a cryogenic liquid for 6 to 10 seconds. A method in accordance with claim 1, wherein the polymer cable component is subjected to a compressive force while the polymer cable component is at the second hardness. A method in which, in the first aspect, the compressive force produces less deformation of the polymer cable component at the second hardness compared to the polymer cable component at the first hardness. A method in the first aspect, wherein the second hardness is greater than the first hardness. A method in accordance with claim 1, wherein the polymer cable component comprises an outer surface, an inner bulk, and an inner surface, and wherein the step of cooling the polymer cable component comprises a step of cooling the outer surface of the polymer cable component. A method in accordance with claim 1, wherein the polymer cable component is a polymer insulator surrounding the circumference of the conductor. A method in accordance with claim 1, wherein the polymer cable component is a fluoropolymer insulator surrounding the circumference of the conductor. A method in claim 1, wherein the polymer cable component is not cooled for more than 10 seconds prior to being subjected to a compressive force. A method according to claim 1, further comprising the step of stopping cooling of the polymer cable component for 5 seconds or less before the polymer cable component is subjected to a compressive force. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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